George Howard Darwin and the “public” interpretation of The Tides

Processes of adapting complex information for broad audiences became a pressing concern by the turn of the twentieth century. Channels of communication ranged from public lectures to printed books designed to serve a social class eager for self-improvement. Through analyzing a course of public lectures given by George Howard Darwin (1845–1912) for the Lowell Institute in Boston and the monograph he based on these, The Tides and Kindred Phenomena of the Solar System (1898), this article connects the important practices of public lecturing and book production–two aspects of knowledge dissemination that tend to be studied as separate entities. Darwin, Plumian Professor of Astronomy at the University of Cambridge and son of the famous naturalist, relied on a diverse material culture when lecturing and producing a book. Giving a new account of Darwin’s scientific work through exploring his adaption of it for broader audiences, this article connects the diverse material culture Darwin employed in talks to the practice of producing a published book. The content of objects demonstrated and the lantern slides projected during Darwin’s lectures evolved to form a book designed to engage broad sectors of society in Europe and the United States. Darwin’s lectures were attended at full capacity, while The Tides was soon printed in numerous English editions and translated into German, Italian, Hungarian, and Spanish.

On October 13, 1897, the Boston Herald announced how "the tide of public interest is just now flowing toward Prof. George Howard Darwin of Cambridge, Eng., who landed in New York last Saturday, and who will arrive in Boston today." 1 By the 1890s, Darwin (1845-1912), Plumian Professor of Astronomy at the University of Cambridge, was already a famous name in Britain and the United States.His visit created a surge of interest among the public of Boston.A member of one of the most prominent scientific dynasties of the age and son of the famous naturalist Charles Robert Darwin (1809-82), George Darwin's reputation emerged from his own research on different forms of oceanic, subterranean, and solar tides, an area of expertise alluded to through the initial metaphor in the Boston Herald. 2 Darwin's main reason for visiting Boston was to give a course of ten lectures on "The Tides" for the Lowell Institute, an annual series of public lectures founded by a bequest of $250,000 from John Lowell Jr. (1799-1836). 3Darwin represents one of the many prominent international Lowell Institute lecturers who visited Boston from the mid nineteenth century, walking in the footsteps of Charles Lyell, Louis Agassiz, Charles Dickens, William Makepeace Thackeray, D'Arcy Wentworth Thompson, Edward Poulton, Alfred Russel Wallace, J. G. Wood, and the Lowndean Professor of Astronomy and Geometry at Cambridge, Robert Ball, who had "paid a high tribute" to Darwin's achievements. 4As Diarmid Finnigan has suggested, many Lowell lecturers spoke on scientific topics and some used the talks as a springboard to embark on subsequent lecture tours of the United States. 5The Lowell Lectures attracted large audiences -around 2,000 people in the 1840s, and each lecture continued to attract about 900 people in the 1890s. 6These audiences came from a broad range of different professions, although many represented the educated reading public of the period and lectures tended to be constructed with a miscellaneous literate audience in mind.Certain aspects of the content were left open for the audience to interpret. 7For many, including Lyell, Wallace, and Darwin, the content of their lectures was either founded on or formed the basis for the content of printed books, emphasizing the close connections between the material aspects of producing a published account and giving a course of lectures for the Lowell Institute.Although processes of lecturing and producing monographs for broad audiences at the turn of the twentieth century have received attention over the last two decades, studies of public speaking and book production have remained disconnected.For example, Bernard Lightman's seminal Victorian Popularisers of Science has examined the processes of devising public lectures.These remained central for delivering information on the sciences to broad audiences throughout the nineteenth century and Lightman has cast important light on the large number of lecturers who developed approaches for conveying complex ideas to the Victorian public through combining aspects of instruction and entertainment. 8Peter Bowler has since successfully argued for the central role of "professional scientists" in producing numerous books aimed at broader audiences, a phenomenon that became widespread in the years around 1900. 9 Bowler has highlighted the transformative importance of photography when conveying information in published works read by a social class anxious for selfimprovement.Different authors' credentials as academic experts who could communicate their research in everyday language added authority to the content of these publications.Prominent names became important to publishers, who relied on them to generate sales. 10eorge Darwin fitted all these qualifications -his family name alone secured audiences for his lectures and book.Still more recently, Josh Nall has emphasized the process of distributing the content of lectures through newsprint by exploring a series of lectures given by Percival Lowell on Mars in February 1895. 11However, it remains the case that limited attention has been paid to the material connections between lectures and the books that emanated from them, developing a set of connected practices in the decades around 1900.
This current study works to unite the practices associated with giving public lectures with the production and sale of a book through examining George Darwin's Lowell Lectures and the complex process of converting these into his only monograph, The Tides and Kindred Phenomena of the Solar System (1898). 12It connects a diverse material culture ranging from the temporary exhibitions, objects, and lantern slide projections displayed during public lectures to the practices employed to reproduce these objects, ideas, and images within the pages of a printed book. 13Lantern slides are central to these processes, and their crucial role in conveying information has recently been recognized in religious contexts, serving both to instruct and inspire a sense of devotion among broad audiences. 14Darwin employed lantern slides to inspire a similar level of awe and devotion in his broad middle-class Bostonian audience, and this article explores the complex processes involved with transferring images projected on the walls of a hall into plates and woodblocks interspersed among the letterpress pages of a monograph.An exploration of these practices casts new light on Darwin's relationship with John Murray's publishing house, which had organized the production of many of his father's works from the 1850s. 15Paper remained central to these processes, as it had throughout the lives and careers of members of the Darwin family since the eighteenth century, and plays a prominent role in the process of exploring the stages between giving public talks and producing books. 16Images represented in lantern projections regularly moved between glass plates and a variety of published accounts, as did the manuscript notes Darwin relied on when lecturing.These words later found themselves set in letterpress and printed in books and articles to surround woodblock and electrotype prints that originated from lantern projections.
An examination of the Lowell Lectures given by George Darwin in the autumn of 1897 and his subsequent book The Tides shows how complex scientific theories were transformed and solidified as printed works for broader audiences.After giving a brief introduction to Darwin's academic work, the initial sections explore his approaches to giving lectures while integrating projected images and demonstrations of scientific instruments to engage his audience.The next section moves onto the processes behind transferring an oral presentation and associated objects and images into a printed book to uncover the complex relationships Darwin developed with his publisher, scientific illustrator, and printer.The final sections conclude by assessing the reception of Darwin's Tides, exploring its numerous editions and translations, the practices Darwin used to convey a set of specific talks to a global audience, and the legacy of this work that extended into the twentieth century.

Recruiting a speaker
The house of Newnham Grange in central Cambridge, the home of George Darwin's family from 1885, regularly received letters from across the globe. 17These came from Africa, India, the Americas, and Australia and included responses to Darwin's many questions on tidal and astronomical movements.Those from the United States always included a mixture of academic and personal correspondence addressed to both Darwin and his wife, Maud du Puy (1861-1947), herself a member of the Du Puy family from Philadelphia and a prominent figure in Cambridge society. 18In May 1896, George Darwin received a letter from the wealthy New England industrialist Augustus Lowell (1830-1900), the principal trustee of the Lowell Institute since 1881, who was responsible for inviting speakers to give lectures. 19Lowell wrote "to ask if it would be possible for you to come to this country next winter 1896-1897 to deliver a course of lectures upon the Tides for the Lowell Institute of this City.Two Lectures are expected each week of an hour's length at $150 or £30 a lecture." 20A week after receiving Lowell's letter, Darwin drafted his response.Writing on May 10, 1896, Darwin declined Lowell's offer, stating that "the preparation of popular lectures on so technical a subject as the tides would take a considerable amount of time. ..it would be December before I could seriously attack the work."However, rather than turning down Lowell's offer altogether, Darwin asked if he could give the lectures in 1897 to "give me the longest notice possible." 21nlike his famous father, the naturalist Charles Robert Darwin (1809-82), whose various evolutionary theories had caused ripples of controversy throughout nineteenth-century society, George Darwin presented the perfect candidate for a lecturer at the Lowell Institute.Darwin's detailed mathematical analyses of the tides fitted with the specifications laid out in John Lowell's will, which stipulated that lectures at the institute should be given while "not engaging in controversy." 22Although not controversial, Darwin's distinct interdisciplinary interests were central for shaping his research.Throughout his life, Darwin rejected the term "scientist" as a "new and mongrel word," believing it was too limiting when it came to the exploration of the natural world and his own interests in combining the fields of geology, mathematics, and astronomy to found the field of geophysics. 23ince moving to Trinity College, Cambridge, in 1868, Darwin had developed interests in the shape, movement, and physical makeup of the earth.His first article on the subject, entitled "On the Influence of Geological Changes on the Earth's Axis of Rotation," built on the work of William Thompson, Lord Kelvin, through assessing that the angle between the earth's equator and its orbit remained relatively constant throughout deep time, suggesting the earth exhibited a plasticity by making rough readjustments to a figure of equilibrium, causing the pole to move about ten or fifteen degrees. 24In comparison, Thompson theorized that the earth was an elastic solid.Darwin adapted Thompson's hypothesis to show that similar results could be achieved by treating the earth as viscous fluid, although he was careful to note that "It will of course be understood that I do not conceive the earth to be really a homogeneous viscous or elasticoviscous spheroid, but it does seem probable that the earth still possesses some plasticity." 25t was Thompson who reviewed this paper and, as a result of Darwin's mathematical talent, wrote a sixteen-page report praising the research.Soon after, Thompson invited Darwin to Glasgow, an initial discussion that stimulated the production of a whole series of papers that elevated Darwin into the scientific elite. 26arwin's interests expanded into oceanic tides in the late 1870s, when he began to commission Cambridge University Press to print tide timetables.In 1891, these cost £10/10s per forty copies and were distributed, with assistance from the British Admiralty, to hydrographic offices across the world. 27Printed tables were then filled out and sent back to Darwin from localities including Aden, Batavia, Puna, Hong Kong, Adelaide, and Cape Town, sending records charting daily changes in the tides over several decades to support Darwin's belief that tides could only be understood through systematic observation. 28As a result, Darwin quickly became, in David Kushner's words, "the government clearing house for the organisation and reduction of tidal observations across the British empire." 29By 1896, Darwin required additional assistance with the volume of calculations, receiving a Royal Society grant of £100 "for payment of computers"highly talented practical mathematicians whose extensive correspondence fills a significant portion of Darwin's archive. 30From the late 1880s, Darwin began to promote this research to broad audiences by giving individual public lectures and publishing illustrated adaptations of these talks in magazines.This developed Darwin's reputation as an engaging public speaker, making him an ideal candidate for a course of lectures at the Lowell Institute.plan of the Huntington Hall, part of the Massachusetts Institute of Technology (MIT).In addition to outlining the precise room used to give lectures, Lowell noted: You will see by the enclosed notice that Stereopticon views (not diagrams) are to be shown at the end of the lecture which was not meant to apply so far as they were needed in illustration of the text, but avoid their too liberal use unless the audience were willing to remain beyond the hour for the pleasure of seeing them. 31cording to the printed notice outlining the proportions of the hall and the specific timings for each lecture, the Huntington Hall contained "ample space" for the "display of maps, diagrams etc." while "when necessary the Institute provides a stereopticon, but the lecturer should furnish the requisite 'slides.'" 32Lowell's communication of a plan of the room to Darwin, identical to that shown on the printed ticket in Figure 1, was essential for allowing Darwin to plan a course of lectures that utilized both slides and demonstrations of experiments from the offset.This presents similarities with figures such as John Tyndall (1820-93), who, when giving Lowell Lectures on light and heat in 1872-3, worried that the large American audiences might not be able to see the equipment across the spacious auditorium and had to find a way to ensure audiences could view his experiments. 33Projection was critical to Tyndall's Lowell Lectures in 1872: it ensured the audience could view enlarged images of the experiments through a variety of lenses and "a magic lantern strongly supported on a platform with wires attached indicating electricity as the source of light." 34It seems that Darwin used similar, if not the same, equipment in 1897.Experiments were typically performed during lectures and integrated with the showing of lantern slides that the institute's bylaws stipulated "should be given at the close of the lecture." 35Rules such as this were most likely a legacy of speakers from the 1870s, who used so many slides it proved to be burdensome for the Lowell Institute's staff. 36Each talk was designed to be an hour in length and "written, or prepared, for the Lowell Institute" and not given elsewhere in Boston before the specified lecture. 37or Darwin, the ability to show slides in lectures was central for conveying complex research to broad audiences.Writing to Lowell on March 17, 1897, Darwin asked, "if you could let me know the size of the slides for the magic lantern, if I should desire to exhibit any of my diagrams in that way." 38  showing projected images at the end of lectures, these needed to be integrated into the main body of the talk.As such, Darwin disagreed with the printed notice, requesting to show slides during his talk, since "I shall require them to explain what I am saying." 39his reflects the importance of engaging an audience through showing a range of images to support the main arguments and ideas given in a popular lecture, and the limited number of slides Darwin proposed to show resulted in the rule of only showing slides at the end being relaxed. 40For example, Robert Ball (1840-1913), Darwin's colleague at Cambridge, had been criticized after giving a course of Lowell Lectures in 1884.The Boston Herald noted that Ball had an "impediment in his speech," while describing his lecturing style as "clergymanic." 41As Lightman has suggested, by the 1880s and 1890s audiences attended public lectures to be instructed and entertained, and it was the responsibility of a lecturer to provide this service. 42Images, portable exhibitions, and displays formed a key part in this process and had central roles in Darwin's course of Lowell Lectures.
Widescale interest in Darwin's lectures was made clear by the Boston Herald, which described Darwin as "a successful explorer in an unknown region of science and [who] has brought back facts of real importance."It was also suggested that "a certain dramatic interest is added to his career from the fact that his father was Charles Darwin, the originator of the Darwinian theory of the origin of species."In addition to emblazoning an article entitled "Professor Darwin Comes Today" with a profile illustration of Darwin, the Herald outlined the popularity of his lectures before they even commenced: "every seat at his [Darwin's] lectures is spoken for in advance and somewhere in the neighbourhood of 900 people will be gathered on Friday evening to hear him." 43Attendees were presented with a Lowell Institute ticket, outlining a seat number and a plan of the hall on the verso (Figure 1). 44Darwin's course commenced on Friday, October 15, 1897, and each subsequent session took place on Tuesday and Friday evenings.There was no tailoff in attendance and the Herald described how Darwin's series was "one of the largest gatherings ever attracted to a purely scientific Lowell Institute course." 45hen it came to his lecturing style, Darwin almost certainly drew on his previous experience.Much of this came from his teaching in Cambridge, giving the Bakerian Lecture for the Royal Society in 1891, and his expanding portfolio of public lectures that he gave for the Royal Institution, the Birmingham and Midland Institute, the Gilchrist Trust, and the Sunday Lecture Society in the 1880s and 1890s. 46Darwin also received advice from Ball, who had an extensive knowledge of how to entertain and engage diverse audiences and experience of delivering a course of Lowell Lectures. 47Interest in entertaining the audience encouraged Darwin to combine his use of lantern slides with an animated presentation style, a practice alluded to in the Boston Herald: 48."Knowledge on Tides," Boston Herald, October 23, 1897, p.12. 49."Knowledge about Tides," Boston Herald, October 16, 1897, p.6. 50.Lowell Institute Scrapbook, "George H. Darwin," "Lowell Institute Records, circa 1837-1943," Houghton Library, Harvard University, 54M-206.51.Hayes, "Geographical Light," 29 (note 13).52.Butterworth, "A Lantern Tour of Star-Land," p.172 (note 47).53.Ibid., p.171.54.William Usborne Moore, Further Report on the Bore of the Tsien-Tang-Kiang (London: Hydrographic Office, 1893).
Prof. Darwin went on to show his audience, with the aid of diagrams, how tides are raised on the surface of the earth by the attraction of the sun and moon.The exposition, though mathematical in character, was given in simple language, and with such intelligibility as to elicit the hearty applause of the audience. 48cturing alongside projected images retained Darwin's large audience, while the illustrative material served to define each session.One journalist described Darwin's practice of giving lectures: "The Professor uses manuscript, and is most unostentatious in manner and speech." 49Subjects Darwin covered included "Observation of the Tide-Wave Motion and 'Selches' in lakes.The 'Bore' or 'Eager.'Tidal force and its Measurement.Effects of the Weight of the Tide-Wave.Oceanic Tides.Tides in Lakes.Analysis of Tidal Oscillations.Tide Friction.Rotating Masses of Fluid.Saturn's Rings and Cosmogony." 50arwin later broke down the two themes of each lecture into twenty chapters reproduced in The Tides.

Projecting pictures and presenting objects
When preparing for his Lowell Lectures, Darwin commissioned a series of lantern slides before departing from England.It is probable that some were produced in Cambridge by firms that manufactured lantern slides for scientific purposes or to depict scenes shown at evening parties in middle-class homes.By the 1890s, scientific lantern slides became easy to obtain.Many British scientific societies integrated the use of the lantern as a standard means for conveying information in their academic and public lectures.This approach was encouraged at the Royal Geographical Society by figures such as Francis Galton, a cousin of Darwin's father, who stimulated the Society's gradual adoption and integration of the magic lantern into its lectures. 51The Royal Astronomical Society played an active role in supplying slides to lecturers.Examples include those Ball purchased for one shilling each during the 1880s and 1890s for use on popular lecture tours. 52n comparison to Ball, Darwin's slides are private commissions designed to sustain the engagement of the audience.This is apparent from the specificity of the images they contain, ranging from photographic reproductions to mathematical diagrams. 53Darwin's first series of photographic slides were shown in his second Lowell Lecture covering tidal bores.These images are based on a series of photographs taken by Captain William Usborne Moore (1849-1918) in 1888 and 1892 when undertaking surveying missions in the estuary of the Tsian-Tang-Kiang, also referred to as Qiantang, near Hangzhou in Eastern China. 54The British recognized the importance of establishing a naval presence in this estuary, an essential maritime artery for accessing export markets in the Chinese interior. 55he photographs Darwin projected were taken by Moore in 1892 when commanding a squadron of British ships led by HMS Penguin.These images came to Darwin's attention after he read Moore's reports of the expedition, published in limited edition pamphlets by the British Hydrographic Office after each surveying mission. 56Darwin received these reports through his links with figures such as Admiral William Wharton (1843-1905) at the Hydrographic Office, who supplied him with data and facilitated the distribution of his tide tables to hydrographic offices across the British empire. 57Moore also published several photographs that Darwin had reproduced as lantern slides.These were designed to present a spectacle for Darwin's audience in Boston, depicting the full force of the largest tidal bore in the world.For example, the image showing the bore passing a headland on October 10, 1892, is a direct reproduction from Moore's pamphlet (Figure 2a).Darwin's next slide shows comparative images of the bore at full force and one minute later where the water is still rough.In the caption, Darwin relied on Moore's account to describe the specific positioning of the "Camera established 20 feet above the River, behind the buttress west of the Pagoda at Hai ning." 58The bore caused considerable damage to Moore's squadron, forcing two of the ships to drag "their anchors three miles up the river." 59arwin gave a simplified account of the lunar origins of tidal bores and the stimulation of the wave through the specific conditions of the depth and shape of the river.However, in the monograph based on his Lowell Lectures, Darwin assessed that "the complete theory of waves would be too technical" for such lectures, giving the rest of his talk over to the dramatic events Moore's squadron experienced, historical accounts of the bore, and his assessment of the proposal to harness tidal bores as a renewable energy source. 60Darwin wrote, "it has been supposed by many that when the coal supply of the world has been exhausted we shall fall back on the tides to do our work," summarizing the power of these natural events and their potential for solving the problems of contemporary society.This contrasts with the opinions reported during Darwin's Lowell Institute course.For example, the Boston Evening Journal published an article entitled "Can't be done: Prof. Darwin says that tides are not available for generating power."After describing how Darwin's audiences "are among the largest ever seen at these lectures," the newspaper emphasizes Darwin's comments on the inefficiencies in harnessing the tides as a source of power, "since the energy of the tides, boundless as it is, does not exist in a form which is easily available." 61This mirrors Darwin's comments in his later monograph, in which he described the inefficiencies of contemporary technology for harnessing this power, emphasizing that tidal energy can only be harnessed in specific places such as tide mills in river estuaries.Darwin's analysis of the tides' potential use as an energy source was utilized by J. B. S. Haldane in The Last Judgement: A Scientist's Vision of the Future of Man (1927), who outlined that "It is suggested that the effect of tidal friction in slowing down the earth's rotation and therefore lengthening the day, was first discovered by George Darwin, a son of Charles Darwin who gave the first satisfactory account of evolution." 62Haldane theorized that the continual use of tidal power would slow the rotation of the earth, resulting in mass extinction of non-domesticated species, climate change, and the diminution of the human population. 63oore's photos and account of the tidal bore on the Tsian-Tang-Kiang led Darwin to describe how "the Chinese regard the bore with superstitious reverence," reiterating a legend concerning how the bore originated from the spirit of a general whose body, after his assassination on the orders of the Chinese Emperor, was thrown into the Tsien-Tang-Kiang, where the vengeful spirit conceived the idea of bringing the tide in from the ocean, destroying Hangchow, at this time the Chinese imperial capital. 64Darwin valued this information, suggesting that "this story is remarkable in that it refers to the reign of an Emperor whose historical existence is undoubted.It thus differs from many of the mythical stories which have been invented by primitive peoples to explain natural phenomena." 65To retain the attention of his large audience, Darwin went on to describe the various social customs surrounding the bore: "The people of Haining still continue to pay religious reverence to the bore, and on one of the days when Captain Moore was making observations some five or six thousand people assembled on the river wall to propitiate the god of the waters by throwing in offerings." 66hared interests in tidal bores and work for the Hydrographic Office placed Moore on Darwin's radar, initiating their correspondence.However, Moore's account of the tidal bore on the Tsian-Tang-Kiang, like many government reports, was a rare publication printed on behalf of the British Admiralty and only distributed to hydrographic offices, institutions, and individuals such as Darwin. 67Darwin's Lowell Lectures are the first attempt to convey this information to a public audience.To make the bore in China more relatable, Darwin describes his attempts to see the bore on the River Severn in England, outlining how "In September 1897 I was on the banks of the Severn at spring tide; but there was no proper bore, and only a succession of waves up stream and a rapid rise of water-level." 68Such was Darwin's obsession with tidal bores, he timed visits alongside family holidays.His daughter, Margaret Keynes, described in her diary their visit to see the bore on the estuary of the Seine in 1904: "a great wave dashing over the quay.A great many people got wet -one man in a thick motoring coat was taken right off his legs." 69n addition to photographic slides, Darwin relied on diagrams and apparatus to convey complex ideas.Writing to the janitor of the Huntington Hall toward the end of his lectures on November 21, 1897, Darwin gave permission "to allow Professor B. O. Pierce of Harvard University to remove my case of models." 70In comparison to earlier lecturers such as John Tyndall, Darwin's smaller audience made using models more feasible, ensuring they played a central role in simplifying the mathematical content of Darwin's lectures.For example, the Boston Herald described how Darwin "showed with the aid of diagrams that the frictional retardation of the earth's revolution by the action of tides is to lengthen the period of the rotation of the earth, and at the same time to lengthen both the day and the month." 71This relates to Darwin's prominent use of scientific instruments in lectures that discussed tides within the body of the earth.When describing the deflection of the vertical, Darwin described how he and his brother, Horace Darwin (1851-1928), the head of the Cambridge Scientific Instruments Company, had developed a bifilar pendulum to measure ultra-microscopic displacements of the ground. 72This was one of several objects Darwin used in his Lowell Lectures both to prove his argument and provide entertainment for the audience.The Boston Herald described Darwin's use of this scientific equipment: To his large audience he gave an interesting account of methods which have been adopted for measuring the tide-generating force of the moon, among them being a bifilar pendulum, constructed by himself and his brother, Horace Darwin.Extraordinary precautions had to be taken to protect this instrument from local sources of tremor.Its movements in a line north and south were magnified by means of a rotating mirror, attached to the pendulum, the results reached were mainly negative. 73is allowed the large audience attending Darwin's Lowell Lectures to gain firsthand experience of the processes of gathering the data used in Darwin's mathematical calculations while proving the existence of viscous tides in the body of the earth.Such was the importance of showing this object that Darwin later commissioned a woodcut for The Tides in which he gives a detailed description of the process of using this equipment (Figure 3). 74Although Darwin's attempts to use the bifilar pendulum in Boston proved unsuccessful due to background interference with the measurements, he described how he used it in secure laboratory conditions in Cambridge, proving that, once all background noise had been eliminated, "it remains certain that a large proportion of these mysterious movements are due to minute earthquakes." 75Darwin also intended for the bifilar pendulum to measure the action of the moon, a usable function after his brother, Horace, perfected the apparatus in the early years of the twentieth century.preparing a lecture entitled "On Meteorites, and the History of Stellar Systems" that he gave at the Royal Institution on January 25, 1889. 78One audience member described how Darwin used Roberts's image while "giving a lecture at the Royal Institution on the Mechanical Conditions in a swarm of meteorites," in which it was suggested the image embodied "the main ideas of the Nebula Hypothesis." 79 Similar images became increasingly commonplace in late nineteenth-century astronomical accounts, although it is important to emphasize that contemporary interpretations of Andromeda were very different to the current conception of a galaxy. 80Writing to Darwin on January 29, 1889, Arthur Nichols, Organizing Secretary of the Sunday Lecturing Society, asked from where he might procure Darwin's images, adding that he would "always acknowledge any permission that may be given to make use of illustrations in lecturing." 81In his response, Darwin noted that the images were the product of his extensive correspondence with Roberts, to whom Nichols resolved to write for permission to use the images in further public lectures.
Darwin started corresponding with Roberts in late 1888 and the chief topic of their correspondence was the supply of lantern slides for public lectures.Writing to Darwin, Roberts noted "that you wish to have a lantern transparency of the neb. in Andromeda for a lecture next month -I will send you one before the end of this month and in the mean time hope for 3 or 4 hours of clear sky to enable me to obtain a better negative than the present one." 82In addition, Roberts produced a sketch of Andromeda on the verso of his letter so Darwin knew what to expect (Figure 4).In comparison to earlier depictions, Roberts suggested that "the two nebulae, one on each side of the minor axis of the Great Nebulae known as p44 & p45," had changed since their original observation by George P. Bond "to the extent of about 25° since the year 1847 or else Bond has wrongly drawn it." 83Roberts's image and description gave Darwin the opportunity to update the lecture he was preparing for the Royal Institution with this crucial data before the new lantern slide arrived, information combined with an image Roberts believed "to demonstrate the truth of the Nebular Hypothesis." 84 Roberts's lantern slide depicting Andromeda arrived in time for Darwin to give his lecture at the Royal Institution, although, owing to cloudy skies, Roberts had to send "a transparency of the photo taken on 1 st October" 1888.Roberts was only able to take  photos of the nebulae infrequently due to the cloudy weather -before 1888, the last time he was able to photograph Andromeda and the other nebulae was in 1886.Roberts maintained that photographs "will convey to you more information than would pages of written descriptions" -a belief Darwin maintained when presenting on the nebulae hypothesis before public audiences. 85antern slides formed a crucial component for Darwin when lecturing on the nebulae hypothesis in the decade before he gave the Lowell Lectures in Boston.In addition to lecturing at the Royal Institution in 1889, Darwin used these slides for numerous public talks across Britain.Darwin intended to publish versions of these lectures and associated slides, the importance of which he emphasized in a letter to the American poet and editor Richard Watson Gilder (1844-1909) when requesting to publish an article in the Century Magazine: "The illustration in question is a very extraordinary photograph made by Mr. Roberts of Liverpool of the nebula in Andromeda.This picture appears to me to prove the substantial truth of Laplace's Nebular hypothesis.As that hypothesis is a step in my lecture this picture is of importance." 86By the time of Darwin's Lowell Lectures in 1897, recent developments in the field of celestial systems meant that he used this slide to outline a very different account of Laplace's theory.Laplace's nebulae hypothesis suggested that the matter that now forms the solar system once existed as a lens-shaped nebula of highly rarefied gas that followed the contours of the current solar system.Initially expanded by heat, Laplace suggested the central section condensed with increased rotation. 87hen in Boston, Darwin used the slide showing Roberts's image of the Andromeda nebula to draw attention to potential flaws in Laplace's theory.Although Darwin acknowledged that some believed Roberts's image showed "Laplace's lenticular nebula with its central condensation," Darwin noted how "other observers, on the other hand, regard it as a spiral nebula seen almost edgewise; and if they are right its formation can hardly be explained according to Laplace's scheme." 88The shape of Andromeda led Darwin to propose a series of challenges to Laplace's theory, suggesting "that every stage in the supposed process presents to us some difficulty or impossibility.Thus we ask whether a mass of gas of almost inconceivable tenuity can really rotate all in one piece, and whether it be more probable that there would be a central whirlpool surrounded by more slowly moving stars."Photographs remained a central reference point for Darwin's critique of Laplace's nebulae hypothesis, ideas that developed as a direct result of his public lectures and subsequent publications, adding that "he has been put into possession of countless accurate pictures of nebulae." 89Roberts remained Darwin's main source of astronomical images.In January 1889 he wrote to Darwin  presentable enlarged transparency for the Lantern, of the Dumbbell neb.& inform you of the result." 90The very different shape of the Dumbbell Nebula encouraged Darwin to exercise caution and not completely discount Laplace's theory, suggesting that among the infinite number of nebulae scattered across deep space, "it is reasonable to suppose that amongst them must be found representatives of the type of nebula from which the solar system sprang." 91Photographs remained a central means for conveying information on deep space to the broad audiences who attended Darwin's lectures.This had become evident to Darwin from 1887, when Paxton Porter, secretary of the Birmingham and Midland Institute, suggested "that other lecturers on astronomical subjects have found Lantern slides to be the most useful in our theatre." 92Darwin gave several lectures in Birmingham from the late 1880s, and the organizers of these events were already aware of the importance of showing lantern slides if speakers were to engage their broad middle-class audience.After showing Roberts's image at the Royal Institution in 1889, Darwin received regular requests for its reuse by public lecturers.Writing to Darwin from Hampstead, Charles Edward Reade described how "I should so much like to have a copy of the nebula in Andromeda by Mr. Roberts," since it conveyed hitherto unseen structures. 93Therefore, Darwin continued to have Roberts's image projected in his talks, including the Lowell Lectures in 1897.It also formed a central component in all his popular publications.Writing from the editorial department of the Century Magazine, Gilder noted his enthusiasm for reproducing such a photograph so long as they are "not engraved and published in any book or periodical elsewhere before they are engraved and published by us." 94 Roberts continued to allow Darwin to publish his photographs since Darwin was a route to social elevation in scientific circles.Roberts wanted his images to be distributed on a global scale, commenting that Darwin was "quite at liberty to publish any of my photos & if it will help you I will with pleasure make you a special enlargement to any scale you may desire of those you want." 95

Preparing to publish
Writing to Lowell on March 17, 1897, Darwin stated that "I presume that short-hand writers are not permitted in the hall, so that I shall retain copyright in my lectures in case I should come to publish them as a book." 96Although he had already given numerous public lectures and published many of these as popular articles in periodicals such as the Century Magazine and Harper's Magazine, Darwin was already planning to publish the content of his Lowell Lectures after their enthusiastic reception in Boston. 97However, Darwin had to make significant adaptions to the published version, commenting in the preface that "This book contains the substance of what I then said.The personal form of address appropriate for a lecture is, I think, apt to be rather tiresome in a book, and I have therefore taken pains to eliminate all traces of the lecture from what I have written." 98his shows that Darwin undertook substantial edits when converting his talks into the content for a book.Other Lowell Institute lecturers, such as Alfred Russel Wallace, who gave a Lowell Institute course in 1886, took a similar approach, basing the main chapters of his book Darwinism (1889) on his lectures while the content of the printed version was heavily worked up from the spoken performance. 99It seems that Darwin was preparing samples of his manuscript for publication while in Boston.Writing from his premises at 50 Albemarle Street, London, Darwin's chosen publisher, John Murray, noted that: I have read the chapter which you kindly submitted to us yesterday with much interest.The subject is a very curious and attractive one, and I cannot but believe that a popular treatise on it will have a good prospect and a favourable reception especially when it has the advantage of your name as author. 100rwin had been familiar with the workings of Murray's firm since his father's death in 1882, when he wrote "to obtain for probate a valuation of my father's books, and generally to know the conditions of your business relations with my father." 101Since the early 1880s, Darwin had maintained a strong business relationship with Murray, acting as a main point of contact in the Darwin family and managing the royalties for his father's works and the numerous new editions.Among the most important was the 1901 edition of The Origin of Species, which had a far greater global impact when compared to earlier editions. 102mages remained essential for Darwin when communicating complex ideas to broad audiences in print -just as they did in public lectures.The Tides contained numerous illustrations made up from a mixture of woodblocks for diagrams and electrotype plates for complex photographic reproductions.Darwin already had extensive experience of producing images for scientific books.During the 1870s, he had produced illustrations for his father's book The Movements and Habits of Climbing Plants (1875). 103Before 1897, Darwin maintained reservations about the quality of illustrations produced by British publishers and the content of the publications in which they appeared.Writing to Gilder about publishing in the Century Magazine, Darwin noted: "I do not much think of sending it to an English magazine, because I want a good woodcut & only the lighter English magazines have illustrations." 104Thus, when preparing The Tides, Darwin explained to Murray that: There will be a considerable number [of images] in the first three chapters & much fewer thereafter.The nature of the text will to some extent depend on the manner in which they are reproduced.I think I can get them done most satisfactorily under my own eyes, and therefore it would be a considerable convenience & advantage to have them done here.Mr. Edwin Wilson is a first rate man & does many illustrations for Scientific journals.He has also done all my diagrams for my lectures.In a good many cases a photographic reduction of the diagram will be best & I should like to go to him and discuss with him how each block is to be done, so as to decide whether photography or redrawing would be best. 105rwin's employment of a specialist scientific illustrator remained a crucial means for him to retain control over the production of The Tides and ensure the images conveyed information that aligned with the theories discussed in the surrounding text.
Wilson's ability to produce illustrations was already well known to many Cambridge professors, the University Press, and the Philosophical Society, of which Darwin was president in both 1890 and 1910. 106By the 1890s, Cambridge University Press regularly commissioned Wilson to produce wood engravings and lithographs, following the increasing assumptions that academic texts should contain images that followed on from the increased prevalence of images in magazines. 107Authors in both the arts and sciences relied on Wilson's images.Examples include M. R. James (1862-1936), who commissioned Wilson to produce the plates accompanying a catalogue of manuscripts in Trinity College.Similarly, Cambridge University Press employed Wilson to produce woodblocks for Charles Godfrey's Elementary Geometry (1903), and by 1913 had become so reliant on images that they purchased Wilson's business. 108For Darwin, extensive experience in producing scientific images made Wilson the obvious choice to produce images for The Tides.This was coupled with Wilson's close geographical proximity: it seems Wilson's business was based on Mill Lane in central Cambridge, close to the main offices for Cambridge University Press.Darwin's home at Newnham Grange was within easy walking distance. 109A close geographical proximity meant Darwin could monitor the quality of the images and avoid problems in the later production process.
Since The Tides was designed for a broad array of middle-class readers who sought to extend their understanding of the world around them, many of the images Darwin commissioned were not his own original creations or commissions.For example, the images of the tidal bore were obtained from Moore's article and the picture of the Andromeda Nebula was taken by Isaac Roberts, although Darwin remained the first person to present this image both as a lantern slide and in a published account. 110Darwin had already reproduced several of these illustrations in magazine articles, and both Roberts and Moore had given him express permission to reproduce their photographs.Other images were sourced from recent publications.When writing to Murray about printing mathematical diagrams, Darwin suggested, "There are several woodblocks which may probably be borrowed from Taylor & Francis (if not destroyed).They were used in Baird's Manual of Tidal Observation.These blocks were on p. 6, p. 3, p. 8 of that book.As I know Col. Baird I am sure that he will give his consent if he knows it is for me." 111 Darwin's extensive network was responsible for supplying many of the images for The Tides.Contributors, including Moore and Roberts, saw Darwin's citation and reproduction of their images as increasing their circulation, elevating their social standing in scientific circles (Figure 2b).
In the end, Wilson produced twenty-four illustrations for Darwin's book, at a total cost of £19/10s, in addition to securing the other blocks from Taylor and Francis, since, as Darwin commented to Murray, he had "a good deal to do with them before." 112Images in The Tides were often set within letterpress that Darwin designed to be read in conjunction with the illustrations.This necessitated an accessible font, with Darwin outlining to Murray that "You may remember that you sent me a sample page as a suggestion for size & Type.I rather prefer the type of my brother's book, to that of the sample; but the difference is only slight." 113This comment relates to Leonard Darwin's (1850-1943) popular treatise Bimetallism (1897), a book the economist John Maynard Keynes (1883-1946)  described as being so popular that "it remained the standard text book on the subject for students until questions in bimetallism had disappeared from the examination papers." 114he typeface of The Tides exhibits many similarities to that used in Bimetallism; both books have capitalized title pages and use large, well-spaced lines of serif font in the main body, showing how George Darwin's book was designed as an accessible publication by which Darwin's Lowell Lectures were transferred into print.
In addition to commissioning new woodcuts and reusing blocks from earlier publications, it was necessary for Darwin and Wilson to adapt several of the electrotype plates used in the Century Magazine.Among these was an image based on Roberts's photograph depicting "Nebula in Andromeda" that Darwin published in the Century Magazine in 1890. 115However, this large, square image with rounded corners did not fit the page size designated for The Tides.Writing to Murray, Darwin noted that "I am however dismayed to find that this block as it stands will not go on to our page." 116However, Darwin outlined a solution: "if however certain margins which are not at all essential are cut off it will just go in. ..tomorrowI will show the figure to Wilson and ask him if it can be cut down without expense." 117Wilson informed Darwin that it was possible to reduce the image and, to better convey this information, Darwin "enclosed a drawing of the illustration of original size, together with the portion to be cut off" (Figure 4). 118The process of editing the original image reflects the substantial differences between transferring single lectures into articles and a series of lectures into a book.The larger compilation put pressure on the page size, limiting the size of the illustrations.This meant Darwin had to rely on Wilson's expertise to arrive at a middle ground in the production process, meeting Murray's specifications for the page sizes.
By September 1898, Murray had commissioned Spottiswoode and Co. to print 1,000 copies of The Tides.Throughout this process, the printers paid attention to Darwin's specifications, including the drafted title page Darwin designed with his friend and neighbor, the classical scholar Richard Claverhouse Jebb (1841-1905). 119By the end of July, Darwin dispatched the "final proof of 120pp to Spottiswoode." 120However, the binding and ornamentation of the book remained a central part of the production process that still required completion.This had to be more attractive to a broad middle-class audience than other textbooks, embodying vestiges of the spectacle evoked through public lectures.For example, earlier British Lowell Institute lecturers who based books on the content of their talks ensured these remained appealing objects to middle-class readers in Britain and America.Examples include Wallace's Darwinism, published by Macmillan in Britain and the United States, a book bound in an attractive dark green cloth with gilded lettering and lines at the head and tail of the spine. 121Darwin had similar concerns about the binding of The Tides.Writing to Murray on July 31, 1898, Darwin presumed "the question of external appearance must be settled shortly.I think buckram has a good appearance, but I don't know about its expense.I think blue would be a good colour.How about the price?" 122Blue buckram follows very similar conventions to Leonard Darwin's Bimetallism that Murray published in the previous year.However, Darwin's Tides had significantly more gilding on the spine and front board, ensuring both its practicality and status on the shelves of middle-class homes.Writing to Murray after receiving a selection of sample bindings, Darwin noted: "I like the blue pattern the better of the two for my book, but I like the way my name is put on the side better in the given sample.I also think there is too much of the gilded wavy lines on the back; three lines above & four or five below would be enough." 123In comparison to books where the author is only named on the spine, Darwin's name appears in gold lettering on both the front board and spine, where it is surrounded by wavy lines to symbolize the subject of The Tides (Figure 5).

Sales, profit, and reception
Murray's anticipation of demand for Darwin's work was recognized by several other publishers.At the start of his course of Lowell Lectures, Darwin received a letter from a New York publisher in which the editor wrote "to express the hope that G. P. Putnam's Sons may be afforded an opportunity of arranging with you for the publication of the volume that will probably be shaped on the material of your lectures." 124However, rather than accepting Putnam's request, Darwin chose to contract with Houghton Mifflin & Co. to publish The Tides in the United States and Canada, agreeing with Murray that "you will send advanced proofs, and that you will communicate with them as to the date of publication." 125 The Tides in the early autumn of 1898 and suggested "for simultaneous publication of the book in England." 126urray's prediction of high sales for the English edition rang true.Out of the 1,010 copies initially printed and marketed for sale in September 1898, Murray had only 211 on hand by the following June and only fifty-eight remained in stock by June 1900. 127In comparison, Houghton Mifflin & Co. were far less successful.Writing to Darwin from Boston in December 1898, the editor commented, "We regret to say that the first sales of your book have not been very large, about 350 copies. ..We hope that the English edition of the book had better success." 128Low sales in North America might well have been a result of Darwin publishing several articles based on his Lowell Lectures in American magazines, meaning the content already had a broad circulation in the United States. 129n addition, Darwin only had a limited influence over the physical construction of the American edition.While the English edition was bound according to Darwin's specifications in dark blue with gold wavy lines embossed on the spine, the American edition was bound in simple maroon cloth.As such, the underwhelming physical appearance of the American edition of The Tides might have had an impact on commercial sales, with the publisher noting that "there will be a certain regular sale of it to libraries, though the demand for a scientific book on a subject which as yet receives the attention of few students is in the nature of things somewhat limited." 130 crucial reason for Houghton Mifflin & Co.'s lack of success was that Murray's edition of The Tides was published and distributed in October 1898.Writing to Darwin on November 11, 1898, Augustus Lowell expressed his gratitude for a presentation copy "of your book on the Tides, which you have so kindly sent me." 131 Similarly, complimentary copies were distributed to those who gave Darwin permission to use their images.A week after Lowell responded, Moore wrote to thank Darwin "for the copy of your work 'The Tides' which I have just received from Mr. Murray and which I shall value very much." 132This shows Murray's edition was released in Britain several months before the American edition, many copies of which were not distributed until early 1899, meaning the main institutions and individuals who were going to acquire Darwin's book in the United States and Canada already had copies of the London edition.When compared to Houghton Mifflin & Co., Murray's success gave the premise for several new editions that Darwin adapted and corrected alongside his ongoing research.
In 1901, Murray published a second edition of The Tides in 505 copies, a book that sold out by 1910. 133This led to the heavily revised third edition appearing in 1911 that Murray published in 1,000 copies. 134The consistent demand for Darwin's work from libraries, schools, and more general readers generated numerous editions that allowed Darwin to update the text alongside advances in the field he founded.In the preface to the 1911 edition, Darwin admitted that "science is always moving onwards, and books on scientific subjects need frequent revision." 135These included heavy revisions to the final chapters, updating Darwin's views on the nebulae hypothesis and the addition of a new chapter on "the figures of equilibrium of a rotating mass of fluid." 136This was adapted from the content of a chapter entitled "the genesis of double stars" that Darwin contributed to Darwin and Modern Science (1909), a book published to celebrate the centenary of Charles Darwin's birth and based on a public lecture series. 137This built on Darwin's earlier work and that of his former doctoral student, James Hopwood Jeans, on infinitely rotating cylinders of liquid in space, leading to the theory of how, as stability diminishes, these cylinders become more pear shaped before the neck breaks to form a satellite.This has direct relevance to Darwin's theory of the initial formation of the earth-moon system in the deep past. 138The necessity to continually update The Tides was clear evidence of its success.In the preface to the third edition, Darwin outlined that "it must generally be satisfactory to an author to find that he has succeeded in communicating to his readers some of his own interest in his subject, and the demand for a new edition of a book affords the most convincing proof of such success." 139New editions of The Tides followed Darwin's continued university and public lectures, for which he had lantern slides made to depict the "Section of a rotating cylinder of liquid," images he reproduced in Darwin and Modern Science and transferred into the 1911 edition of The Tides. 140arwin's work either sold well or consistently after its initial publication in 1898, for which he received an author's royalty of 15 percent "on the advertised price of all copies sold in England." 141This is a very different author's royalty when compared to the twothirds profit Darwin and his siblings received from Murray for the new editions of his father's On the Origin of Species (1898) and Descent of Man (1901). 142The smaller royalty margin reflects on the commercial viability of Darwin's Tides.In comparison to the Origin, of which Murray printed 7,000 copies in 1898 and another 14,075 per printing of the new 1901 "popular impression," George Darwin's textbook had a more limited audience and it took Murray longer to shift the stock. 143This was already apparent after the 1901 edition sold out in 1909, when C. E. Lawrence wrote to Darwin from Murray's offices to state that "Of the 500 copies printed in 1901 only about 20 remain on hand, the sale in recent years has been slow." 144After the 1911 edition was published, Murray informed Darwin in the following April that "the other day you asked me how the new edition was moving; I see that we printed 1006 copies and up to the present we have by sale and presentation disposed of close to 300 copies." 145Sales were hindered by Darwin's sudden death from pancreatic cancer in 1912, meaning dispersal of The Tides was no longer stimulated by his public lectures and teaching in Cambridge.
After Darwin's death, the royalties from The Tides were divided between three of his children, Charles Galton Darwin (1887-1962), William Robert Darwin (1894-1970), and Margaret Keynes (1890-1974). 146The book continued to sell at about thirty to eighty copies per year before it finally sold out in 1927. 147Darwin's brother, Leonard, was appointed as his main literary executor, responsible for ensuring the transfer of the royalties and the authorization of any new editions and translations.This became a pressing issue since just before his death in 1912, George Darwin received a letter from the Spanish naval captain Leon Herrero stating, "I intend to translate your notable book The Tides (third edition) into Spanish." 148Darwin granted the rights, although it was up to his brother, Leonard, and eldest son, Charles, to manage these translations.Charles permitted Herrero to preface the Spanish edition with an obituary of his father, noting in a letter to Murray that "I think the best notice of him was one which appeared in the 'Observatory', and I should think the translator could get all he wants from that." 149 In comparison to many of the translations published during Darwin's lifetime, for which he personally approved the quality of the production, Darwin's death meant he had limited influence over the Spanish translation.This was by no means the only foreign translation of Darwin's work.The third edition of 1911 saw the simultaneous publication of a second German translation, the first of which came out in 1902. 150The Tides was also translated into Italian (1905) and Hungarian (1904). 151Writing in 1904 to Radó von Kövesligethy (1862-1934) in Budapest, Darwin communicated, "I have today received two handsomely bound copies of my book, and I feel I must thank you personally for the interest you have taken in its publication," adding that "the book is decidedly better looking than the English edition, and I regret my inability to read your language when I turn over the pages." 152he rapid initial sales of The Tides and its translation into four different languages resulted from its broad reception among educated society.Darwin's respective publishers, including John Murray and Houghton Mifflin & Co., in addition to those in Germany, Italy, Hungary, and Spain, ensured the book was well advertised and reviewed in newspapers.Murray authorized the publication of a review in the London Morning Post in which it was suggested that Darwin's book acted "as a stepping-stone between the primer and the advanced work," adding that "the reader will find that, with a fair understanding of astronomy, it will not be difficult to follow the discussions on the hypotheses advanced."153 This is a very similar level of praise to that Darwin's peers gave the work.Writing in the journal Science, the American engineer, physicist, and mathematician Robert Simpson Woodward (1849-1924) took a similar line to the popular press, commenting that Darwin had "produced a charmingly interesting and instructive book, which may be read with profit by those who know much as well as by those who know little on the tides."154 Woodward stressed that Darwin's book served to supply a valuable general knowledge of the tides through condensing complex mathematical theories into an engaging general account.
Although the merits of Darwin's book remained the most prominent, it did have some detractors.Writing to the editor of the London Morning Post, J. H. S Moxly, Chaplain of the Royal Hospital, Chelsea, wished to "warn your readers against accepting, without inquiry, the statements of even so-well a teacher as the author of the work in question," believing that Darwin's comments on vertical attraction were inaccurate and would be seen as obvious errors to all with "an elementary knowledge of hydrodynamics." 155ther critics viewed Darwin's work as too complex for a general audience.Writing in one brief note someone going by the pseudonym "mariner" suggested "the theory by which he [Darwin] explains the Tides is really very hard to swallow, even by a 'simple sailor.'" 156This reflects the limitation of Darwin's Tides to those who had access to higher levels of education -a similar audience to those who were attracted to Darwin's lectures.

Conclusion
Darwin's Lowell Lectures and subsequent monograph on the tides connect the diverse content and material culture of public lectures with the complex processes used for producing a printed book at the turn of the twentieth century.Central to understanding this process is Darwin's use of images, the content of which he transferred between the lantern slides he had projected for large audiences at the Lowell Institute through to the woodcuts and electrotype plates produced for and printed in each edition of The Tides.The main purpose of these images, ranging from tidal bores in eastern China to the first photographic representations of deep space, was to engage and entertain a broad, albeit an educated well-to-do, audience through the mediums of an animated public lecture and a printed book.These mediums facilitated both a temporary and a more permanent model for conveying the complex ideas Darwin developed to found the field of geophysics by the turn of the twentieth century.As such, Darwin presents a key insight into the processes used by numerous public lecturers when converting talks into monographs, which saw a surge in popularity at the turn of the twentieth century.
The relative success of The Tides was connected to Darwin's consistent public, academic, and university lectures.As we have seen, many of Darwin's public lectures were given for the Birmingham and Midland Institute, the Gilchrist Trust, the Royal Institution, and, of course, the Lowell Institute, who all catered for well-educated middle-class audiences who also had the income to purchase a monograph based on these talks.A gilt spine would have been an appealing decoration on a bookshelf in a middle-class home.In addition to giving numerous talks in Britain and the United States, Darwin lectured for scientific and public audiences at events such as the International Geodetic Congresses in Stuttgart (1898), Paris (1900), Copenhagen (1903), Budapest (1906), and Cambridge (1909), where Darwin and his wife Maud entertained numerous delegates at Newnham Grange. 157In 1905, Darwin traveled to South Africa as the president of the British Association for the Advancement of Science (BAAS), a tour launched to solidify British rule in the region in the immediate aftermath of the Boer War. 158Darwin's diary gives numerous descriptions of his own and his colleagues' public and academic lectures as he journeyed overland between the Cape and Cairo.For example, Darwin gave the opening address for the BAAS on Tuesday, August 15, 1905, and when visiting the Kimberley diamond mine on September 5, Darwin noted that "At half-past eight in the evening Sir William Crookes gave a lecture on diamonds.The lecture was an admirable one and his experiments succeeded to perfection, but he made the enormous mistake of lecturing for two hours so that everybody was weary at the end." 159Similarly, Darwin described numerous garden parties and civic events at which he gave brief public addresses, such as the opening of the Bulawayo Museum. 160arwin's continued public and academic lecture tours acted as an international advertising campaign for The Tides.This was combined with his public lectures around Britain and consistent university teaching, which generated sales from the British public and his students at Cambridge.The lantern slides Darwin commissioned  these trips, acting as central illustrative aids for his talks while also serving as promotional material for his book.As Darwin's research progressed, so too did the content of his lectures and the number of slides he showed -something also represented by the increased content formed from text and images in each new edition of The Tides.After Darwin's death from pancreatic cancer in 1912, Murray's accounts show that sales of The Tides slumped to between fifty and eighty copies per year, with the final eighteen copies selling out in 1927. 161he close material connections between Darwin's lectures and The Tides show how these approaches to conveying information developed alongside one another.Darwin's lectures and book on tides present a very different relationship between print and public talks when compared with previous speakers at the Lowell Institute and other British lecturers in the United States such as Tyndall, Richard Proctor, and Peter Kropotkin, who relied on newsprint to promote their talks and ideas to mass audiences.In comparison, Darwin's interest in producing a book published in multiple editions allowed for the continued public promotion of his research as it progressed, showing how Darwin's academic research was intimately bound up with his attempts to convey complex ideas to broader audiences.It provides a framework for the practices used by other British Lowell Institute lecturers who published books based on their talks, perhaps the most notable being Wallace's Darwinism, which was published in three editions and several different languages during his lifetime.Darwin's theories on tides and the evolution of satellites and the wider solar system remained valid for much of the twentieth century.A renewed interest in Darwin's field by the early 1960s encouraged the San Francisco publisher W. H. Freeman to publish yet another edition of The Tides -a paperback aimed at a broader audience.In the preface, the editor paid tribute "to the remarkable progress achieved by Sir George Darwin in a field essentially founded by him as it is to the lack of progress ever since."162

Figure 1 .
Figure 1.An entrance ticket and seating plan for George Darwin's Lowell Lectures on "Tides" in 1897.54M-206, Houghton Library, Harvard University.

Figure 2 .
Figure 2. (a) (Left) The photograph published in Moore's Further Report on the Bore of the Tsien-Tang-Kiang (1893).(Right) The lantern slide Darwin showed in Boston in 1897.Reproduced with the kind permission of the Master and Fellows of Darwin College, Cambridge.(b) One of a series of woodcut illustrations depicting the bore on the Tsian-Tian-Kiang published in Darwin's Tides and Kindred Phenomena of the Solar System.

76 77.Figure 3 .
Figure 3.A woodcut diagram depicting Horace Darwin's bifilar pendulum that George Darwin demonstrated during his Lowell Lectures.This image was first published in The Tides (1898) and printed in all subsequent editions.

Figure 5 .
Figure 5.The spine and front cover of Darwin's The Tides (1911).All the editions published by John Murray were decorated in a similar manner.
8. Bernard Lightman, Victorian Popularisers of Science: Designing Nature for New Audiences (Chicago, IL: University of Chicago Press, 2007), pp.viii-ix.9. Peter J. Bowler, Science for All: The Popularization of Science in Early Twentieth-Century Britain (Chicago, IL: University of Chicago Press, 2009).10.Ibid., pp.1-2, 10. 11.Joshua Nall, News from Mars: Mass Media and the Forging of a New Astronomy, 1860-1910 (Pittsburgh, PA: University of Pittsburgh Press, 2019), pp.135-59.12. George H. Darwin, The Tides and Kindred Phenomena of the Solar System (London: John Murray, 1898).13.For more detail on the material culture of scientific lecturing, see Bernard Lightman, "Lecturing in the Spatial Economy of Science," in Aileen Fyfe and Bernard Lightman (eds.),Science in the Marketplace: Nineteenth-Century Sites and Experiences (Chicago, IL: University of Chicago Press, 2007), pp.97-134; Emly Hayes, "Slidescapes: Three Royal Geographical Society Lectures by Vaughan Cornish," Early Popular Visual Culture 17 (2019): 71-88; Emily Hayes, "Geographical Light: The Magic Lantern, the Reform of the Royal Geographical Society and the Professionalisation of Geography c. 1885-1894," Journal of Historical Geography 62 (2018): 24-36; Richard Crangle, Mervyn Heard, and Ine van Dooren (eds.),Realms of Light: Uses and Perceptions of the Magic Lantern from the 17th to the 21st Century (London: The Magic Lantern Society, 2005).

Darwin quickly realized that rather than
46. Francis Darwin, Memoir of Sir GeorgeDarwin in Scientific Papers by Sir George Howard Darwin, Vol.V (Cambridge: Cambridge University Press, 1916), p.xxvii.Numerous invitations to lecture for these institutes can be found in Darwin's correspondence.Many are followed by letters concerning the specific arrangements for travel and showing lantern slides.47.Lightman, "Lecturing in the Spatial Economy of Science," pp.97-9 (note 13); Mark Butterworth, "A Lantern Tour of Star-Land: The Astronomer Robert Ball and his Magic Lantern Lectures," in Richard Crangle, Mervyn Heard, and Ine van Dooren (eds.),Realms of Light: Uses and Perceptions of the Magic Lantern from the 17th to the 21st Century: An Illustrated Collection of Essays by 27 Authors from Six Countries (London: Magic Lantern Society, 2005), pp.162-73.