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Alan Turing’s Pens

(This page published April 1, 2024)

Reference Info Index | Glossopedia  ]

What kind of pen would a genius use? For one genius, at least, we know the answer. Meet the pens of Alan Turing.

Alan Mathison Turing was born June 23, 1912, in Maida Vale, London, England, to Julius Mathison Turing, the son of a clergyman, who was then on holiday from his position in the Indian Civil Service, and Ethel Sara Turing (née Stoney), whose father, Edward Waller Stoney, was chief engineer of the Madras Railways. Enrolled at the age of six in St Michael’s, a primary school in St Leonards-on-Sea, Sussex, England, Alan was quickly recognized for his outstanding intelligence. The school’s headmistress noted, “I have had clever boys and hardworking boys, but Alan is a genius.”

The Pen That Alan Invented

Between January 1922 and 1926, Alan studied at Hazelhurst Preparatory School in the village of Frant, also in Sussex. While there, he made it a weekly practice to write to his parents on Sundays; and in a letter written when he was 11 years old, he told them of a fountain pen that he had invented. Shown below are the two pages of that letter, written on Easter Sunday, April 1, 1923. Note that in his header, Alan crossed out “Easter,” perhaps playfully, and wrote in “fools day”:

Some images on this page can be clicked or tapped to display magnified versions for more detail. When you mouse over a clickable image, the image will give a visual indication by growing a little, and the mouse pointer will change to a magnifying glass. On a touchscreen device, touch and hold your finger on the image briefly to see if it reacts. If it does, you can tap it.

Here is an expanded and enhanced view of the pen itself, including Alan’s parts list and a smudged partial fingrprint:

Pen diagram, 1923

For its nib, Alan’s invention used a standard flexible steel pen made to fit a dip penholder, held in place by a cork plug. At the distal end of the pen was the “squishy end of [a] fountain pen filler,” which would have been the bulb from an ordinary eyedropper. Alan had devised an arrangement, possibly in the form of a groove along the cork’s periphery where the nib fitted, such that squeezing the sac slightly would force ink forward to the nib.

Alan did not explain how he filled his pen. He also probably did not know that the pen was a case of parallel evolution. There are two possibilities here:

Either way, Alan had not yet solved all of the engineering challenges: he complained in his letter that the pen “keeps on getting clogged.” Letters written after the letter above indicate that he continued to use his new invention for some time. He had also developed an ink that he referred to as “my patent ink,“ mentioning it to his parents in a letter dated February 11, 1923, a month and a half before the letter shown above. A pronounced unevenness of flow is apparent in the letter shown above; it might be due to the irregularities of the pen or to the ink, or to both. It is not clear when he resumed the use of ordinary pens.

In 1926, Alan advanced to Sherborne School, a boarding school in Sherborne, Dorset. There he met Christopher Morcom, who was about a year older than he, and the two boys soon formed a bond of friendship that was based on their mutual interest in mathematics. Alan fell in love with Chris, who appreciated Alan’s affection but was more reserved and did not return it. Alan is shown here at the age of 15, in Westcott House at Sherborne.


Image provided courtesy of Sherborne School Archives.

Although he was a remarkably good student, doing well in Latin and mathematics, Alan was known to his schoolmasters, even including the headmaster, as untidy in his person, often covered with ink smears and splotches, with handwriting to match. According to the Latin master during the 1924 term, “[A]ll his work is spoilt by bad writing & lack of neatness.’ During the 1926 summer term, his housemaster wrote, “I am quite pleased with his start. He’s a very grubby person at times. I hope Ireland will de-ink him.” By 1928, however, he had improved greatly.

Alan was devastated when Chris, having drunk unpasteurized milk some years earlier, died of complications from bovine tuberculosis at the age of 18 in February 1930. Alan desperately wanted to believe that Chris’s mind was somehow still alive. As he coped with his grief by diving more deeply into the mathematics and science studies that he had shared with Chris, he became fascinated with the problem of how the mind and brain work, and that scientific turn of mind was an underpinning for his later mathematical development, especially in the analysis of codes and ciphers.

Alan graduated in due course from Sherborne, with more than a handful of honors that included the King’s Medal for Mathematics in 1931. In October of that year, he went up to King’s College, Cambridge, which had granted him a scholarship of £80 per annum. While there, he studied mathematics, receiving a First in Part II of the Mathematical Tripos in 1934. He was elected a Fellow of the College in 1935.

The Pen That Alexander Munro Invented

Fountain pen
Fountain pen
Photos © 2024 Larry Hanks. Used with permission.

Munro applied November 3, 1915, for a patent on what became the Research Fountain Pen, and he was awarded British Patent No 1915.06570 February 24, 1916. This was the last of his six assorted pen patents, including a well-engineered bulb filler that was patented in 1908. The basis of this final patent was a twin-reservoir system with the forward reservoir much smaller than the rear reservoir, an arrangement that mitigated the likelihood of blotting or flooding while writing by reducing the volume of air that could be expanded by heat.

A plunger-operated valve connected the two reservoirs, with the plunger either spring loaded or on a long-pitch screw thread. In either case, the operating knob would be rotated through a quarter or half turn to release it for operation or lock it afterward. Shown here are several figures from the patent.

Patent drawing

Munro was clearly determined to keep others from working around his patent by using different implementations. Figure 3 illustrates how the system was to work with a spring-loaded plunger; when depressed against the spring, the plunger opened the valve. Figure 5 shows it with a plunger on a long-pitch screw; screwing the knob counterclockwise would raise the plunger to open the valve. In this figure, the “business end” of the pen was a stylographic point, and the plunger’s front end was extended to provide a stop to keep the wire and its weighted carrier from falling backward out of the tip. Figure 4 shows a variant design for the valve, in which the valve was opened by moving a “piston” into a part of the barrel whose internal diameter was enlarged to allow the passage of ink, as it was in the Onoto pens manufactured by Thomas De La Rue & Company and would later be in Sheaffer Vacuum-Fil pens and their clones.

Munro described an unusual, and very effective, approach to the problem of sealing the back end of the barrel where the plunger passed through it. Instead of a packing around the shaft, he described a short length of rubber tubing, securely sealed at one end to the back of the barrel and at the other end to the shaft itself. This design is illustrated clearly in Figure 4.

The pen could also be built as a self-filler. Figures 6 and 7 (below) show two methods of accomplishing the filling action. Figure 6 illustrates a system that worked much like the usual Onoto/Sheaffer plunger system, with the addition of a valve through the plunger that could be opened or closed by turning a small secondary knob (identified as the “projecting head,” callout 10). Figure 7 illustrates a modified bulb-filler in which the bulb (callout 17) had a cap (callout 16) molded at its distal end. Pulling the cap off the end of the fixed breather tube allowed the bulb action to fill the pen. Replacing the cap closed the upper end of the breather tube, and using the bulb would then force ink through a small hole in the tube’s wall, whence it could flow downward into the forward reservoir. It is not clear which of these methods, if either, was used in production pens, which were self-fillers.

Patent drawing

Further shielding Munro from potential copycats, Figures 6 and 7 illustrate both straight-cap and cone-cap designs while Figure 7 also illustrates a tubular feed.

As Munro described the invention, the forward reservoir was to be approximately one-third the size of the rear portion, and the writer would recharge the forward reservoir from the rear reservoir after writing out the contents of the forward reservoir. The patent asserted, “The invention may be used in conjunction with any usual device for sealing up the reservoir when the pen is carried in the pocket, but the effect of the invention tends so much in the direction of greater cleanliness that any sealing up device is rendered largely unnecessary.”


Amidst claims of extravagant praise from all quarters, the ad did not stint on lavishing its own encomia on the Research Fountain Pen:

Automatically declines to blot or flood during writing, or to leak in the pocket. May be carried point downward in the pocket, although the pen is NOT sealed up.”

Farther down were explicit claims of the Research Fountain Pen’s virtues, described as “two new physical properties not to be found in any former variety of pen; viz. — (1) The absence of blotting, flooding, and leaking in the pocket; and (2) The ability of the pen to maintain upon the writing-point a uniform and unvarying quantity of ink.”

Upon his graduation from King’s College, Alan attended Max Newman’s lectures on the Foundations of Mathematics. Newman encouraged Turing to consider whether it might be possible to apply some mathematical process to a mathematical statement to determine if the statement was provable. Alan spent 1935 and 1936 working on such a proof. This work also included a description of a “Universal Machine,” now known as the Turing Machine, a mathematical model that could implement any possible computation, so long as it could be represented as an algorithm.

In 1936, Turing applied, and was accepted, to a postgradaute program at Princeton University. During his time at Princeton, he wrote frequently to his mother; in a three-page letter written on October 14, most probably in 1936 (first page shown below), he described to her work he was doing on codes and ciphers. The ink flow from the pen he used to write this letter is very consistent, as would be expected of his Research pen.

Turing Card
Alan Turing
Image © Princeton University Archives. Used with permission.

A Chemically Colorful Digression


This letter gives us vital information about the Research Fountain Pen. Because the green pen that turned ruby red also became “quite transparent,” we know that the Bakelite in at least some of Munro’s pens was formulated without a filler material. Formulations without fillers are more fragile than hard rubber, and fillers were introduced to work around this weakness; but formulations with fillers are opaque.

The final version of the Research Pen (Mark III) appears to have been made of Perspex, a high-quality acrylic resin similar to Lucite or Plexiglas. Shown here is a Mark III pen in clear Perspex, probably for use as a demonstrator. Note the wall dividing the two reservoirs.

Fountain pen
Fountain pen
Photos © 2024 Larry Hanks. Used with permission.

Postscript: A New Enigma

The Research Fountain Pen that Christopher Morcom’s mother had given to Alan in 1932 was of high quality, and it was a remembrance of his first love; but, as described above, it was lost in 1937. The enigma now lies in identifying the fountain pen or pens that Alan Turing might have owned from Autumn 1937 until his untimely death in 1954.

  1. Archive Centre, King’s College, Cambridge, The Papers of Alan Turing, K/1/1.  Return

  2. Hodges, Andrew, Alan Turing: The Enigma, Princeton University Press, 1983, 48.  Return

  3. “Current Topics and Events,” Nature: A Weekly Illustrated Journal of Science, May 19, 1923, 692.  Return

  4. -page advertisement, Supplement to Nature, December 30, 1923, ii.  Return

  5. Archive Centre, King’s College, Cambridge, The Papers of Alan Turing, K/1/43.  Return

  6. U.S. Customs Service, List or Manifest of Alien Passengers for the United States Immigrant Inspector at Port of Arrival, September 27, 1937, List No 92.  Return

  7. Hodges, Andrew, Alan Turing: The Enigma, Princeton University Press, 1983, 174.  Return

  8. Turing, Alan Mathison; Graduate Alumni Records, AC105-03, Princeton University Archives, Department of Special Collections, Princeton University Library.  Return

  9. Etymology uncertain; there exist several theories. The most likely explanation was given by Czesław Betlewski, a technician at the Poles’ interwar Cipher Bureau: workers at B.S.-4, the Cipher Bureau’s German section, christened the machine a “bomb” (also, alternatively, a “washing machine” or a “mangle”) because of the characteristic muffled noise that it produced when operating.  Return

  10. Pease, Roland, Alan Turing: Inquest’s suicide verdict ‘not supportable’ (, June 26, 2012; retrieved February 9, 2024.  Return

  11. Murray, Donald, letter to the editor, Supplement to Nature, December 1, 1928, 845.  Return

The information in this article is as accurate as possible, but you should not take it as absolutely authoritative or complete. If you have additions or corrections to this page, please consider sharing them with us to improve the accuracy of our information. My thanks to Rachel Hassall, Archivist, Sherborne School; Tom Davies, Assistant Archivist, King’s College, Cambridge; Rosalba Varallo Recchia, Reference Specialist for Special Collections, Princeton University; and Larry Hanks, whose 2006 Writing Equipment Society Journal article on the Research Fountain Pen inspired me to ask him if he would photograph the pens for me and who also generously ran a final accuracy check, for their kind assistance in making this article possible.

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