Photograph 49 is the Key to Understanding the History of Rosalind Franklin’s DNA Photograph 51

Abstract

This essay, co-authored by a historian of science and an X-ray crystallographer, sheds new light on Rosalind Franklin’s Photograph 51. We refute the infamous claim that, unlike James Watson, Franklin failed to see the picture’s potential significance for interpreting the helical structure of DNA. Rather, Franklin decided to take Photograph 51 precisely because she knew that key parameters of DNA’s B form helix could be calculated from the resulting image. We show that she had in fact already made those calculations — on her earlier Photograph 49 — and she reused the same DNA sample for Photograph 51 to create a better-centered but otherwise identical diffraction image that would be suitable for publication. Thus Photograph 51 was not the result of an experiment in need of analysis, but was refined documentation for calculations that she had already performed on the earlier photograph. We argue that colleagues and later commentators did not merely overlook Franklin’s original reason for creating the strikingly clear and informative Photograph 51, they rhetorically erased her skill and judgment by describing it as though nature spoke for itself through the image — and to Watson, but not to Franklin.

Introduction

Rosalind Franklin’s Photograph 51 (see Fig. 1) became famous because James Watson wrote that it spoke powerfully about the secret of life. “The instant I saw the picture,” he narrated in his controversial memoir The Double Helix, “my mouth fell open and my pulse began to race” (1968b, p. 167).¹ It was early February 1953 and Franklin’s estranged colleague Maurice Wilkins had shown Watson this X-ray diffraction image of DNA in a state known as the B form.² As Watson described it, he immediately recognized that the pattern on Photograph 51 “could arise only from a helical structure […] mere inspection […] gave several of the vital helical parameters” (1968b, pp. 168–169). Spurred on by seeing the image and learning of some measurements Franklin had taken of the B form diffraction pattern, Watson and Francis Crick began a fresh effort to build helical models of DNA and within a few weeks managed to produce their double helix.³

While Watson’s book made Franklin’s Photograph 51 famous, his story gave the impression that she had not been able to recognize its significance the way he did. Consequently, many scientists, journalists, and biographers have sought to explain Franklin’s apparent neglect of a picture that, in retrospect, was so clearly suggestive of a helical molecule (Table 1).

Table 1 Key dates in the history of Photographs 49 and 51

By consensus, what happened when Photograph 51 was taken in early May 1952 is that Franklin put the picture aside and did nothing with it, instead devoting months to studying the crystalline form of DNA known as the A form. In late February 1953, her notes show, she began to use Photograph 51 to understand the B structure. By then it was too late: she was still working when Watson and Crick solved the puzzle a few days later.

Several overlapping reasons have been given for Franklin’s apparent initial disregard and subsequent delay: she was only interested in the A form of DNA; she had only captured a B form pattern in Photograph 51 by accident, and as such considered it a distraction; she was resistant or even hostile to the suggestion that DNA was a helix. For Horace Judson, writing what remains the best-known journalistic account of Watson and Crick’s discovery, this added up to something like willful deafness on Franklin’s part. “The pattern shouted helix,” Judson lamented, but for nearly ten months she “turned her back on her own discovery of the B structure of DNA and her own best evidence that [it] was helical” (Judson 1979, p. 135).

We write here to contend that Photograph 51 shouted “helix” so clearly because Rosalind Franklin intended it to do so. She had already photographed the very same sample of DNA used for Photograph 51, and analyzing the prior diffraction pattern, Photograph 49 (Fig. 2), led her immediately to a number of significant conclusions about the dimensions of a helical DNA molecule. She then created Photograph 51 for the purpose of reproducing that valuable diffraction pattern in a better-composed image that would be suitable for publication. Whereas Watson and others have portrayed Photograph 51’s combination of visual excellence and theoretical significance as a kind of happy accident that Franklin failed to exploit, it was the desire to merge those qualities in a single exposure that had in fact driven her to take Photograph 51. By recapturing Franklin’s original motivation, we are in turn able to explain the subsequent actions which have been misinterpreted by her supporters and critics alike.

We will present our revisionist account first and then use it to reassess portrayals of Franklin. We begin with a short but detailed explanation of how photographs 49 and 51 were created around the beginning of May 1952 and how Photograph 51 came to serve its purpose as an image intended for circulation. We analyze the later emergence of claims that Franklin had ignored or misunderstood Photograph 51, and argue that these criticisms echoed longstanding tropes about the role of women in science and of photographs as scientific evidence.

Fig. 1

Rosalind Franklin’s personal copy of Photograph 51. On this glossy photographic print Franklin noted “NaDNA ‘Structure B’” upon the reverse (History of Molecular Biology Collection, Box 10, Folder 15, Science History Institute. Philadelphia)

The Significance of Photograph 49

The key to understanding why Franklin took Photograph 51 lies in her notes about a previous picture. It was the forty-ninth in a series of seventy-eight diffraction images she and her graduate student Raymond Gosling captured with a Philips micro-camera (see Fig. 2) at King’s College London in 1951 and 1952.⁴ Months before taking Photograph 49, the pair had established the existence of two distinct structural forms of DNA, and they had begun to manipulate samples intentionally to create them. The A form possessed an almost crystalline structure and gave diffraction patterns with many spots, potentially offering a great deal of information for structural analysis (by calculation of Patterson maps).⁵ DNA could be converted to the B form at high relative humidity, yielding a simpler diffraction pattern with too few spots for similar (Patterson) structure calculations. Franklin had discussed her discovery of the distinct A and B forms in a colloquium at King’s on 21 November 1951 and documented them in an annual report of 7 February 1952, but her results were not otherwise published.⁶

Franklin’s annual report of February 1952 also laid out a research plan that she appears to have followed closely until she moved from King’s College to Birkbeck College in the spring of 1953. Her goals were twofold: (1) to determine what caused a given DNA sample to exhibit the A or the B form, and afterward, (2) to characterize both forms initially through Patterson analysis of the more complex but data-rich A pattern.⁷

Photograph 49 was created two months later in the course of a lengthy series of experiments aimed at completing the first of these objectives. Franklin’s stated hope was that these experiments would also reveal the best techniques for capturing sharp DNA diffraction patterns. As hoped, it was during this period of systematically manipulating the humidity levels at which samples were stored and photographed that she and Gosling produced what they retrospectively considered their best ever A form pattern (Photograph 42 of early February 1952) as well as their best B form photographs in May.

Completed on the morning of 2nd May 1952, Photograph 49 showed the result of aiming an extremely fine X-ray beam for three days and nights at a fiber that had been pulled into a fine thread from a drop of gel-like concentrated DNA solution.⁸ The beam emerged from a collimator at the front of the camera and met the sample fiber, which was mounted and held in place across the orifice by two drops of glue, immediately inside the camera, just 15 mm in front of the X-ray film that recorded the diffraction pattern (see Fig. 2). Because space within the camera was so tight, they employed an unusual technique to prevent the main (undiffracted) X-ray beam from overexposing the center of the film. Instead of blocking the main beam with a small circular piece of heavy metal such as lead between the specimen and the film, as was conventional in larger cameras, they punched a hole through the centers of all the stacked films and allowed the undiffracted beam to pass right through the films and out of the back of the camera, through a small fluorescent screen that facilitated camera alignment (the holes can be seen in the film and camera body shown in Fig. 3).⁹ Franklin and Gosling controlled the relative humidity of the DNA sample throughout the days-long experiment by passing hydrogen gas that had been bubbled through an aqueous salt solution of defined composition and concentration into the body of the camera.¹⁰

As with the trials that preceded Photograph 49, they would learn the result of the experiment by removing and developing a stack of two or three small, hand-cut pieces of film from where they were held inside the camera body during the exposure (see Fig. 3). Each of the duplicate (or triplicate) films would show an even smaller X-ray diffraction pattern about 2.5 centimeters in diameter. On this occasion, they had used two pieces of film marked in Franklin’s handwriting as 49A and 49B (see Fig. 4).¹¹

These Photograph 49 films showed an unprecedentedly sharp version of the diffraction pattern produced by DNA’s B form (Fig. 2). Franklin and Gosling accomplished this by using a sample that had become irreversibly locked into the high-humidity B structure, meaning that it could be mounted taut in the camera and photographed at the lower 75% humidity level that ordinarily produced an A form pattern.¹² The resulting fine definition made it possible to use the photograph for more precise analysis than any previous B image had allowed, and Franklin therefore gave it her prompt attention. This immediacy is evident from a separate series of notes that were headed “(49) 49B Rough measurements on projection,” dated 2 May 1952 — the very same day she and Gosling had developed the films.¹³ These notebook pages began with measurements of the new diffraction pattern, which the pair enlarged by projecting it onto a piece of white cardboard, and Franklin’s notes progressed in short order to making general conclusions about the B structure of DNA. She noted that the molecule showed repeats occurring every 34 Å, meaning it was about 25% longer per repeating unit than the drier, more crystalline A form she had already begun to analyze.

From the day Photograph 49 was taken, Franklin interpreted the pattern as indicative of a helix.¹⁴ Other evidence indicates that she already had a helical interpretation of the B form structure in mind, and now she calculated how many layers of purine and pyrimidine bases there must be “per turn of helix (if there is a helix).”¹⁵ If the bases were spaced 3.4 Å apart, as she and other researchers believed, then her calculations suggested that there would be exactly ten nucleotide-base layers in each lengthwise repeat of the molecule. In her notes, she phrased the finding more generally: “there is an integral number (or single fractional number) of residues per [34 Å] turn.”¹⁶ Later, in 1954, Watson and Crick acknowledged that they had built their double helix as a model of the B form with its 34 Å axial period containing ten base layers per turn, which, Watson and Crick crucially realized, were complementary base pairs rather than individual bases. It is not widely appreciated that these parameters were originally established in Franklin’s analysis of Photograph 49.¹⁷

Fig. 2

Photograph 49. This glass-plate negative shows an identical diffraction pattern to that of Photograph 51, seen in Fig. 1, except that the pattern is cropped by poor alignment between the film holder and the X-ray beam; the upper 3.4 Å arc is almost entirely lost. Both exposures used the same DNA sample under the same conditions (KDBP 1/1/0868, King’s College London Archives). Courtesy King’s College London

Today Photograph 49 survives in its entirety only as a negative-image contact plate of film 49B held at the King’s College London archive (Fig. 2). The photograph is remarkable for two distinct reasons. First, it vividly captures the very same diffraction pattern known so well today from Photograph 51. Secondly, however, a portion of the famous pattern has been cut off. Through our examination of the camera Franklin and Gosling used in 1952, we can explain how this must have happened. The photographic films were held in place by a flat metal bracket whose edges were bent around a backing plate that the films rested against (Fig. 3). This holder has a slightly irregular circle of roughly 2.5 cm diameter cut out to allow the diffracted X-rays to hit the films, and the glass negative of 49B illustrates that this holder had become misaligned with the X-ray beam and the DNA sample. In consequence, the upper part of the pattern is cropped to such an extent that a large, arc-like region now familiar from Photograph 51 (Fig. 1) does not appear in the image. This missing arc, like its symmetrical counterpart which appears at the bottom of Photograph 49, is caused by the 3.4 Å spacing between each layer of nucleotide bases in the molecule.

As we have seen, this inadvertent cropping did not prevent Franklin from using Photograph 49 in her analysis and calculations. She had captured enough of the pattern to be able to discern that one of the 3.4 Å arcs was located on the tenth meridional layer line of the pattern and to understand the implications for quantifying the layers of bases stacked in a single 34 Å turn of the helical molecule. Photograph 49 was a sharp and usable image but, because of the equipment malfunction, it was poorly composed and thus less than ideal for public presentation.

Fig. 3

X-ray micro-camera and film. This recent picture illustrates how X-ray films were prepared for the Philips micro-camera (KDBP 6/4/7, King’s College London Archive) that was used to take photographs 49 and 51. From left to right: the front of the camera body, removed and viewed from the inside; a piece of X-ray film backing paper showing how films were cut to the appropriate size; the film holder (above) and a piece of developed X-ray film (below) showing that the region of the film exposed to X-rays was determined by the cut-out in the holder; the camera body back, containing the rectangular platform against which one or more small pieces of film were held in place by the film holder. The film and backing paper are surviving artefacts from Wilkins’ 1953 research with Herbert Wilson, which included replications of Franklin and Gosling’s work using different sources of DNA (K/PP178/2/8, Wilkins Papers). Photograph by Alistair Sponsel, July 2026

Franklin therefore decided to retake the photograph. On the evening of 2 May 1952 – still the same day she first saw Photograph 49 – she began the notebook entry for Photograph 51: she would use the same specimen from 49, the same X-ray setup, and the same 75% relative humidity within the body of the camera.¹⁸ The only thing distinguishing this from being an exact repeat was, as she wrote, that Photograph 51 was taken “with [the] holder centered over [the] collimator so as to include both 3.4 [Angstrom] arcs.”¹⁹

Photograph 49 had been a research image, the result of an experiment. Photograph 51 would be the exact opposite: a refined image taken after the fact to document that experiment’s particularly successful outcome.²⁰

This relationship between Photographs 49 and 51 emerges all the more clearly when Franklin’s notes about them are compared with earlier entries in her laboratory notebooks. She had by then established a note-taking routine well suited to the open-ended trials characteristic of Photographs 1–49, with two distinct parts for each entry. The first section, written before the photograph was taken, provided details of the experimental set-up, including the date and time when X-ray exposure commenced. Afterward, Franklin would record the date and time when she and Gosling ended the exposure and then complete a second section, for which she customarily left a few lines empty, giving a brief indication of how the experiment had turned out.

Initially, she wrote about Photograph 49 using her standard format. She first specified which DNA sample she was using, the relative humidity at which it was maintained, and the source of the X-rays. Three days later, she filled in the space below to report that this trial had produced a “V[ery] good ‘wet’ photo” (meaning a very good photo of the B form). However, she then turned to a fresh set of pages in the notebook and filled them with the analyses we discussed above. Headed with the very date the photograph had originally been developed, this passage of notes filled far more space in her laboratory notebooks than did the discussion of any single previous DNA diffraction pattern, indicating that she immediately found this version of the B pattern to be strikingly important.

The entry for Photograph 51 was unprecedented in a completely different way. This was the first instance in Franklin’s DNA laboratory notebooks where she was able to write down in advance what details the diffraction pattern would include (namely, both 3.4 Å arcs) and the first occasion when she specified that correcting the cropping of a previous photograph was the reason for taking a new one. As an understandable consequence, Franklin did not bother to fill the lines at the end of entry 51 where she would normally have described the result of the photograph. Indeed, the empty space stands out starkly on a pair of pages otherwise densely filled with the initial conditions and the results of the surrounding experiments. As discussed below, later commentators have misinterpreted this omission as the act of a person who had just conducted a potentially crucial experiment, but who didn’t appreciate its significance. Rather, as we have shown, Photograph 51 was not an experiment at all in the sense that trials 1 to 50 had been. It was, in fact, the product of Franklin’s decision to invest four days of X-ray time into a known outcome. The investment made sense precisely because she valued a high-quality photograph of the helical B form diffraction pattern.

Franklin and Gosling did not immediately publish Photograph 51. Later commentators, armed with the knowledge that it would be less than a year before Watson and Crick built their double helix as a physical model of the very B form structure Franklin and Gosling discovered and characterized, have criticized Franklin for directing much of their effort during the rest of 1952 to analyzing the A form. However, what critics describe as Franklin’s discovery — and subsequent apparent neglect — of evidence for the crucial B form structure of DNA looked different from her perspective and in the context of her broader research objectives. Franklin’s stated objectives, as we have seen, were to understand the relationship between and interconversion of the two forms of DNA. Photographs 49 and 51, and her analysis of the former, which revealed the key parameters of a helical structure, represented an important and successfully achieved milestone. It is only with hindsight that we view the B form structure as the only important goal, and the structure of DNA. DNA clearly had more than one structure and Franklin wanted to solve both of them.

Fig. 4

The handwriting on individual films of photographs 49 and 51 (KDBP 1/1/0867–868, King’s College London Archives) compared with entries in Franklin’s notebooks (FRKN 1/1, Franklin Papers; reproduced with the kind permission of the Trustees of the Franklin Archive)

By completing Photograph 51, Franklin now had good images in hand of both the A form and the B form. From here, she turned to the second major objective of her established research plan: detailed structural analysis beginning with the crystalline A form, whose pattern offered more data for analysis than the paracrystalline B form. The results of several months’ work led her to conclude that this crystalline structure was likely a double-chained molecule, and in February 1953 she turned back to Photographs 49 and 51 to assess whether the B structure in turn showed “evidence for [a] 2-chain […] helix.”²¹ That the B form photographs indicated a helical structure however, was not in doubt, as indicated by her notebooks. By the end of February, as she was leaving King’s College for a position at Birkbeck College, she and Gosling had drafted three papers, two of which would contain Photograph 51 when they were published later that year.²² Meanwhile, since Gosling was to remain at King’s to finish his PhD under Wilkins’ supervision, Franklin directed him to give Wilkins the diffraction photograph that Wilkins in turn showed Watson.²³

For all the investment Franklin originally made to capture a publication-worthy version of the B pattern, when it came time to publish Photograph 51 she took yet another step to refine the image. In early March 1953, she turned over film 51C to be duplicated onto a durable glass slide negative that could, in turn, be used to produce positive photographic prints for submission.²⁴ The slide, which survives and is numbered 867 in the biophysics unit’s indexing system, became the basis for published reproductions.²⁵ This is evident because published images of Photograph 51 show the diffraction pattern centered within a circular border even more precisely than it had been when the pattern was originally developed on film. The perfected cropping was achieved by placing masking tape on the glass plate itself (see Fig. 5). The figures of Photograph 51 in both of Franklin and Gosling’s 1953 publications (1953a and 1953b) that included it show the ultra-refined cropping from the glass plate.

Fig. 5

A composite image showing how Photograph 51 was further cropped for publication. Left: a hitherto unpublished print of Photograph 51 showing that the circular region of exposed film had been larger than necessary to succeed in capturing the full diffraction pattern (HMBC Box 10, Folder 15). Center: the glass plate negative of film 51C with red masking tape used to create a new, smaller circular margin centered precisely on the diffraction pattern, which left a penumbra that can still be seen faintly through the tape in the lower-right quadrant of the slide (KDBP 1/1/0867). Right: Photograph 51 as it appeared in publications, shown here in the 25 April 1953 issue of Nature (Franklin and Gosling, 1953a)

Rethinking Rosalind Franklin’s Reputation in Light of Photograph 49

The myth that Franklin had failed to see value in Photograph 51 arose as a consequence of Watson’s 1968 memoir The Double Helix. The book appeared fifteen years after the events in question, ten years after Franklin’s tragically early death from ovarian cancer, and six years after Watson, Crick, and Wilkins shared the Nobel Prize for their studies of DNA. The book caricatured her as both a machine-like researcher and as a woman with emotions she could not control. In Watson’s telling, her “years of careful, unemotional crystallographic training” meant that she was producing sharper diffraction photographs and consequently more detailed measurements than anyone else (Watson 1968b, p. 69). However, she would erupt into defensive outbursts at any attempt to help her interpret these proprietary data, making life an “emotional hell” for her colleague Maurice Wilkins (Watson 1968b, p. 167). Indeed, Wilkins supposedly showed Photograph 51 to Watson in a moment of solidarity when Watson had invoked Franklin’s “hot anger” by suggesting to her face that “she was incompetent in interpreting X-ray pictures” and needed to “learn some theory” (1968b, p. 166).

Watson’s harsh portrayal of Franklin inspired many reactions, one of which came from her friend and former Birkbeck colleague Aaron Klug. Klug had inherited many of Franklin’s King’s College research records, and he now sought to understand what she had known about DNA, and when. After finding her 1951–1953 laboratory notebooks, he studied them carefully and circulated annotated photocopies for discussion with Wilkins and others (including historian Robert Olby, who was then working closely with Crick while doing research for a planned book). This flurry of activity in 1968 revealed that the well-known published B form pattern had been called Photograph 51 in her notebook and that it had been taken at the beginning of May 1952.²⁶ Wilkins reacted by declaring it a “real tragedy” that, in keeping Photograph 51 to herself for the rest of year, Franklin had allowed Watson and Crick to race ahead of the King’s group. “I looked at that B form picture,” Wilkins said in reference to receiving it from Gosling in January 1953, “and there it was, you can see the helix right there on the picture, but she refused point-blank to see it.”²⁷

Fig. 6

Rosalind Franklin in a 1950 photograph by the crystallographer Vittorio Luzzati (History of Molecular Biology Collection, Box 10, Folder 14. Science History Institute. Philadelphia)

Sentiments like Watson’s and Wilkins’ had a profound impact on the historical treatment of Franklin’s work. The question became, how did Franklin fail to discover the double helix while she possessed the photograph that supposedly had spurred Watson and Crick’s success?²⁸ For example, consider how the journalist-historian Horace Judson wrote about her in his celebrated 1979 book The Eighth Day of Creation, which was based on extensive interviews with all the participants except the late Franklin herself. Knowing with hindsight that Photograph 51 was the B picture she would later publish, he used it as a narrative device to portray a singular moment when Franklin decisively failed. “The pattern shouted helix,” Judson wrote, and it even “whisper[ed]” the other details of the B form structure. Although he mentioned the analysis she had performed on Photograph 49, his characterization was that Franklin merely “thought briefly and tentatively about No. 49” and “[t]here she stopped.” By underestimating the novelty and significance of these calculations and, more importantly, by misjudging why she had chosen to take Photograph 51, Judson interpreted the lack of notes about the retaken photograph as a sign that she had “turned her back on her own discovery of the B structure” (Judson 1979, p. 135). We do not believe that Franklin ever turned her back on the B form. Deciding to take Photograph 51 was not a moment of failure, but a mark of her future commitment.

We have seen that Watson portrayed himself as immediately hearing the helix’s metaphorical shout from Photograph 51. He went on to insist throughout his life that Franklin had not been a sufficiently good scientist to see in Photograph 51 the truths that he had instantly recognized in the B form pattern. In a 2008 interview, for example, he said Franklin “clearly wasn’t interested in theory very much” and had neglected to pursue the B form even though it “was the perfect helical thing.”²⁹

These phrasings portrayed Photograph 51’s simple, sharp B form diffraction pattern as a natural object rather than a human-produced research product — as though it had occurred spontaneously under Franklin’s watch rather than being generated and photographed on purpose. In Judson’s telling, the DNA molecule “whispered” and “shouted” directly to those who saw the picture, rhetorically erasing the role Franklin played in revealing nature’s secrets (1979, p. 135). We have seen that Wilkins went even further, speaking as though Franklin had been concealing nature’s secrets by possessing Photograph 51.

The conceit that nature could speak directly to Watson through Photograph 51 echoed language that dates back to the earliest use of cameras by scientists. Advocates of the new technology claimed that photography, by reproducing natural objects mechanically and therefore without human bias, supposedly allowed nature to speak for itself. As historians Lorraine Daston and Peter Galison have shown, this combination of rhetoric and technology stemmed from the 19th-century craze for achieving “objectivity” in scientific research. Although technique and even creativity were actually required to make nature (seemingly) imprint itself on a photographic plate, the objective scientific photographer’s goal was to render this work invisible (Daston and Galison 2007, p. 133). One of Franklin’s contemporaries, the great crystallographer J. D. Bernal, alluded to this process shortly after her death. Having pointed out that Franklin captured “among the most beautiful X-ray photographs of any substance ever taken,” Bernal remarked on the “skill” that had allowed her to make those photos appear to be “effortless.”³⁰

However, merely highlighting Franklin’s technical acumen risks damning her with faint praise for her contributions to the discovery of the double helix. It is one thing to possess the skill necessary to let a molecule seemingly speak for itself through a beautifully clear photograph, but it is another thing to be able to discern which specimen must be heard in order to solve an important scientific puzzle. To flip Watson’s deprecating remark on its head, this does require an interest in theory. It requires knowledge and judgment. In Franklin’s case, not only had she recognized the conceptual value of the B form diffraction pattern captured in Photograph 49, but she had also devised the original series of humidity experiments that revealed the B form’s existence and enabled her to capture it so clearly.

Franklin was an accomplished, creative, and self-directed researcher, but Watson’s Double Helix cast her in the role of a technical plodder, unimaginatively toiling over samples, laboratory equipment, measurements, and calculations.³¹ Later efforts to praise her as a skilled crystallographer (but by implication nothing more), often reinforce a long tradition of women’s scientific activities being treated as rote work.³² Recently, as Franklin’s public profile has risen considerably, her role in the hands-on work of crystallography has, in turn, been called into question. In what we consider to be an oversimplified description of a multi-day, multi-instrument collaborative undertaking, Gosling is now regularly credited as the sole individual who took Photograph 51.³³

Evidence from throughout Franklin and Gosling’s notes illustrates her leadership of, and thorough involvement in, both the intellectual and technical aspects of this collaborative research. Her handwriting on the films of photographs 49 and 51 (see Fig. 4) indicates that she was present when the films were loaded into the camera, but both Franklin and Gosling were likely aided by other women working alongside the King’s College biophysicists. Freda Ticehurst was the unit’s scientific photographer and manager of the dark room. She, in turn, had assistance from the likes of Lucille Heller, who volunteered in the biophysics unit in 1950–1951 and recalled “I remember helping Gosling set things up, and I think I helped sometimes with taking the X-rays, and I helped Freda Ticehurst, the lab photographer, develop some of the images.”³⁴ Gosling himself recalled the assistance and collaboration he and Franklin received from one of the biophysics unit’s workshop technicians, Len Pitches, who modified and even built cameras and other apparatus to their specifications.³⁵

Our case study of the relationship between photographs 49 and 51 provides only a glimpse at the full arc of Franklin’s activities as a DNA researcher.³⁶ However, even within this short paper we have witnessed her pursuing a full spectrum of scientific activities: designing a highly consequential series of experiments, tapping the skills of her student and technical staff while working alongside them in the X-ray room, accumulating data and carrying out careful measurements, perceiving the value of her results, and also showing a persistent intention about how to make the result we focused on here — the B diffraction pattern — appear in the most arresting possible form when it was published. She created Photograph 51 to serve as evidence of a helical DNA structure, of her laboratory's technical virtuosity, and of her own scientific judgment.³⁷