The Philosophical Breakfast Club

by Laura J. Snyder

  Herschel read his first paper on photography to the Royal Society on March 14, 1839; in this paper he coined the name “photography,” to replace Talbot’s more vapid “photogenic drawing.” (He had already suggested the term to Talbot in February.)43 The paper also introduced the terms “positive” and “negative.” Later Herschel would be responsible for another crucial term in the new art, referring to taking a photograph “by a snap-shot.”44 Herschel withdrew the paper before publication, requesting that only an abstract be printed as a “note” in the society’s Proceedings. Herschel later explained that he had withdrawn the article because he did not wish to interfere with “Mr. Talbot’s just and long antecedent claims” for priority in inventing the process.45

  In September Herschel made the first photograph on glass: an image of his father’s forty-foot telescope, which was pulled down two months later. By precipitating freshly formed silver chloride onto a piece of glass, a light-sensitive surface was made to adhere to it. Exposed through the lens in a camera, an image was formed, and fixed with a wash of the hyposulphite. The fixing of this negative was so perfect that half a century later his son, Alexander Stewart Herschel, was able to produce twenty-five paper prints from the original plate.46 By the 1850s, Herschel’s technique for taking photographs on glass negatives and printing paper copies—rather than Daguerre’s more cumbersome process—would be deployed by the French themselves, in documenting Baron Georges-Eugène Haussmann’s complete renovation of Paris under Napoléon III.47

  DURING HIS EXPERIMENTS, Herschel realized that the “hypo” needed to be used carefully; if overused, it deposited sulfur compounds into the photographs, spoiling some and weakening others. Hyposulphite of soda was expensive and difficult to obtain. Herschel wondered why plain water could not be used to wash out or fix the photographs. As he put it in the notebooks, “Why should it not—the nitrate is a [water] soluble salt?” He tried several times, but without good results. Finally Herschel realized that the problem was the water quality. Slough was now becoming an urban area of London, with the problems of a big city—such as pollution. “I observe here that my pump water is now at least five fold more loaded with muriates than it was five or six years ago,” Herschel mused, “so much that it is quite unusable when silvery solutions are concerned.” He found that by using “snow-water,” which was purer, he could gain success. Some of his water-fixed photographs remain to this day. But he quickly realized that ensuring such purity of the water would not be commercially viable.48

  Slough had become a popular place to live, thanks in part to the young Queen Victoria, who resided in nearby Windsor Castle. The Great Western Railway had knit together Slough and the center of London, making travel between them quick and easy. When the Italian astronomer Giovanni Amici had visited London in 1827, Herschel insisted that Amici stay at Herschel’s house at Slough, noting that the seventeen-mile trip to London would take “only” two and a half or three hours by coach. When Talbot made his trip to Slough in February 1839, he marveled that it had taken a mere thirty-eight minutes to arrive by train.49 Queen Victoria’s first train ride was from Slough to London, in 1842; the train averaged forty-four miles per hour. Victoria asked Albert to tell the railway company she had not enjoyed the trip at all, and to please go more slowly in the future.50

  However, this increase in convenience to Slough brought changes that Herschel could not abide, especially after the idyllic time he had enjoyed at the Cape Colony. As he explained to his aunt, “Since the good old times the neighborhood is so changed that it seems we are already in another country. A railroad runs close to the village and brings down hundreds of idle people and all day the road in front of the house is kept in a riot and dust with the railroad omnibuses.”51 There was also another problem with living in Slough—a seventh child had been born soon after the Herschels’ return from the Cape, and the house at Slough was becoming too small. Herschel began to seek a more countrified place to live. In the summer of 1839 he found a house near the village of Hawkhurst in Kent, in a large park surrounded by hilly countryside, reminiscent in some ways of their beloved home in South Africa. In April of 1840 the family relocated to the new house, called Collingwood. It was a good idea to move, as the prolific couple would go on to have five more children, for a total of twelve.

  Once he relocated, Herschel devoted himself to making all the necessary calculations from the data gleaned from his four hundred nights of observations at the Cape Colony. It was a long and irksome process, one that he conducted himself, without the help of paid computers. His friends, especially Whewell, lamented the lavish expenditure of his time and effort upon “mere arithmetic.” Whewell tried to persuade him to hire assistants, but Herschel persisted in his solo labors. It would take over seven years before Herschel completed the work. During this time he was constantly pulled between his need to finish the calculations and his desire to experiment on photography. Margaret admitted to Caroline during this time that she had not given up “spurring him on with his Cape calculations, for so much of his valuable time was spent in making these observations, that I am determined not to be happy until the work is completed and out of his hands. Am I not a very cruel wife!” John lamented to her, “Don’t be enraged against my poor photography. You cannot grasp by what links this department of science holds me captive—I see it sliding out of my hands while I have been dallying with the stars. Light was my first love! In an evil hour I quitted her for those brute and heavy bodies which tumbling along thro’ ether, startle her from her deep recesses and drive her trembling and sensitive into our view.”52

  After a winter in which there were fogs so thick and opaque that ships routinely collided,53 the sun finally broke out, and Herschel could not resist returning to his experiments in the spring of 1840. As Talbot wrote to him, “The present weather is the fairest and most settled, since the birth of photography.” Herschel soon told his aunt that “we have had and are still having a most magnificent summer—such a one as I do not remember ever before in England.”54 At the end of August, Herschel succeeded in producing a color photograph of the entire light spectrum. By concentrating the prismatic spectrum with a large lens of crown glass, and aiming it onto the prepared paper, Herschel found that the resulting image was tinged with colors that differed based on their location on the spectrum: red rays gave no tint, orange a faint brick red, the orange/yellow rays a pretty strong brick red, the yellow a red passing into green, the green a dull bottle green passing into blue, the blue/green a dull and somber blue, almost black, the blue a black, the violet a black passing into yellow with long exposure, the part beyond the violet (the ultraviolet), a purplish black.55 Herschel excitedly told Talbot that “it holds out I think a very fair promise of solving the problem of coloured Photographs!”56

  By the fall of 1840, Talbot too had made a breakthrough, one that secured his method’s success over Daguerre’s. He found a way to amplify the effect exerted by light in his camera. He discovered that a weak exposure, because of darkness or haze, insufficient to produce a visible image, could be brought out by an additional wash of gallic acid and silver nitrate. That is, the latent image could be made apparent. Talbot immediately began to speculate on the types of objects that could be photographed: “Sun behind a cloud. Moon. View by moonlight. Fire. Lighted candle. Vase, at first screened from sunshine.… White clouds. Diffraction bands. Spectrum.”57 No longer did Talbot’s method rely wholly on the sun to reduce the silver on the photographic paper. Now he could take a faintly exposed photographic plate and amplify the exposure through chemical means. He called the new type of images “calotypes,” for the Greek kalos, or “beautiful.” In December of 1840, Herschel was distressed to learn that he, and not Talbot, had been awarded the gold medal of the Royal Society for work on photography, specifically for his paper on the photographic action of the solar spectrum. In 1842 the Royal Society finally recognized Talbot’s achievement, and awarded him its prestigious Rutherford medal for his work.

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bsp; HERSCHEL’S INTEREST in botany, born during his time at the Cape Colony, was put to use in his photographic experiments. Herschel began to experiment with floral dyes, using the petals of fresh flowers in the place of the silver salts to produce photographic papers. He would crush the flower petals to a pulp in a marble mortar, sometimes with the addition of alcohol. The juice expressed by squeezing the pulp into a clean linen or cotton cloth was spread on paper with a flat brush, and dried in the air.58 The benefit of this process was that while the silver salts darkened when exposed to light, the dyes usually bleached under the exposure, thus producing a direct positive. Herschel’s experiments showed that different extracts produced different tints under varied wavelengths of light. This process yielded rich single-color photographs, many of which remain vivid today. Had Herschel persisted in these experiments, he would almost certainly have produced a full-color photograph, by superimposing different-colored layers with sensitivities to different primary colors.59 He submitted fifteen colored photographic copies of engravings and mezzotints—prepared by casting luminous rays on substances derived from plant sources—to the Physical Section of the British Association meeting in 1841.60

  One of his color processes used an iron pigment known as Prussian blue rather than vegetable dyes. This process, dubbed by Herschel the “cyanotype,” became the most commercially viable of the paper photographic methods in the 1840s, and survived into the twentieth century as the basis of the architect’s blueprint. By washing paper with a solution of ferric ammonium citrate, an iron salt, Herschel created photographic paper highly sensitive to the action of light. After half an hour or an hour’s exposure to sunshine, followed by a wash in a solution of yellow potassium ferrocyanate, a white image would appear on a bright blue background.61

  This cyanotype process led to the publication of the first book to use photography: Anna Atkins’s Photographs of British Algae: Cyanotype Impressions, first part published in 1843. (Talbot would not publish the first volume of his own book, The Pencil of Nature, until the following year.) Anna Atkins was the only daughter of John George Children, who had been a friend of the Herschel family since youth—he was also a sworn enemy of Babbage, having won out over Babbage for the job of junior secretary of the Royal Society in 1826. Anna had been raised by her father after her mother’s death in childbirth, receiving from him a highly scientific education, which was still quite unusual for a woman of her time. She also had access to his large and well-equipped laboratory, which had been the setting, in 1813, for the convergence of thirty-eight of Britain’s leading chemists—Wollaston and Davy among them—for dinner and a demonstration of Children’s huge voltaic battery.

  As a young woman, Anna produced 250 detailed engravings to illustrate her father’s translation of Jean-Baptiste Lamarck’s classic work, Genera of Shells. In 1825 she married John Pelly Atkins and moved to Halstead Place in Kent, where she began a collection of dried plant specimens later donated to the Botanical Gardens at Kew. She was made a member of the Botanical Society of London in 1839—it was one of the first scientific organizations to admit women as full members (her father was, at the time, the society’s vice president).

  Children and his daughter knew Talbot and Herschel well. Atkins probably knew Richard Jones as well; his home in Sevenoaks was only five miles from Halstead Place, and Herschel was a frequent visitor to both Atkins and Jones. Children had been the chair of the Royal Society meeting when Talbot discussed the details of his process of photogenic drawing in February 1839, and he would have discussed it with his daughter soon afterwards. In 1841 Children told Talbot that he had ordered a camera for Anna.

  During the summer of 1843 Atkins began working on a book about algae, using the cyanotype method of photography. In her preface she explained that “the difficulty of making accurate drawings of objects as minute as many of the Algae and Confervae, has induced me to avail myself of Sir John Herschel’s beautiful process of Cyanotype.”62 It is likely that Herschel himself had taught her the process. By October she began issuing parts of the book. Each part consisted of a series of original cyanotype plates that were contact prints, made by placing specimens of algae that had been washed, arranged, and dried on top of a sheet of prepared paper, and set in the sun; the exposed sheet was then washed, dried, and flattened. The resulting book consisted of 389 captioned plates, and fourteen pages of titles and text. At least a dozen copies of the book were made and distributed to interested scientists, including Talbot and Herschel (Herschel’s copy now resides in the collections of the New York Public Library). This means that Anna, perhaps with the help of her father, prepared thousands of sheets of cyanotype paper by hand. His giant battery could have been used to produce the ferric ammonium citrate and the potassium ferrocyanide needed for the process. This monumental accomplishment took ten years to complete. Not only was the cyanotype method relatively inexpensive and long-lasting, but it produced a deep blue color that was particularly appropriate for the algae, which appear to be floating ethereally in a cerulean sea.63

  ALMOST AS SOON as the new technology had been invented, Herschel began to devise plans for harnessing it to the train of science. He encouraged Anna Atkins in her work, pleased to see photography put to the use of botany, an improvement over the botanist’s former reliance on the camera lucida. Herschel also saw that photography would be valuable in astronomical observations, particularly for the recording of sunspot activity. First, though, a means needed to be developed for the sun’s light to be used for making an image without overexposing it. Warren de la Rue would soon invent a device that could take solar photographs, and it would be deployed at the Kew Observatory for making the observations suggested by Herschel. But before then, Herschel had a chance to attempt to introduce photography into an expedition being readied for the Antarctic region, an expedition he and Whewell were responsible for promoting.

  While at the Cape of Good Hope, Herschel had been making hourly observations of weather phenomena on the days of the equinox and the solstice: the equinox occurs twice a year, in March and September, when the sun is vertically above a point on the equator; the solstice, when the sun’s position above the earth is at its northernmost and southernmost extremes, also happens twice a year, in June and December. One typical diary entry reads: “Rose at 5½ and commenced hourly observations for the Month—which I carried on till 4 AM of the 22nd when Margt relieved me and took the 2 last hours.”64 Another: “At 6 AM began the Hourly Obsns for the Winter Solstice.…—Occupied with them the whole day.—at 5PM went to bed. Got up at 9 and sate up all through the night and till 3 sweeping the intervals.”65 Barometric pressure, air temperature, and the intensity of light from the sun were all measured. At the same time Herschel was soliciting meteorological observations from colleagues around the globe: Albany and Boston in the United States; Mauritius; Brussels; Van Diemen’s Land (now Tasmania); and others.66 Part of his motivation was to gather the data that might make it possible to confirm his father’s suspicions about the correlation between the weather and sunspots. Did periods of greater sunspot activity mean more sunlight reaching the earth’s atmosphere, or more cloud cover: more light or more shadow? (Solar scientists are still debating this question today.) But another issue at stake was the relation between atmospheric conditions and the intensity of terrestrial magnetism.

  As William Gilbert had concluded in 1600, in his monumental work De Magnete, magneticisque corporibus, et de magno magnete tellure (On the Magnet, Magnetic Bodies, and the Great Magnet the Earth), the earth is a giant magnet, with north and south magnetic poles. This was why, Gilbert argued, compasses always pointed north, a fact that had been known for centuries, but had previously remained unexplained.

  The use of the nautical magnetic compass had made possible the “age of exploration” and the increased trade, naval defenses, and imperialism that went with it. For this reason, Gilbert’s contemporary Francis Bacon considered the compass one of the three technologies that defined the modern age (the ot
hers were the printing press and gunpowder). But no one had yet been able to account for just how the magnetic compass enabled sailors to find their way around the seas.

  By describing his experiments showing that the earth was a giant magnet, Gilbert provided such an explanation. The compass did not point north because of a magnetic Pole Star, as Christopher Columbus had thought, or because of a large magnetic island at the north geographic pole, as others had previously speculated. Rather, it pointed north because it was being attracted to a magnetic pole of the earth. Gilbert correctly reasoned that the core of the earth was iron, thus explaining the earth’s magnetic force.