The Hand of John Snow

The Mode on Communication of Cholera is a scientific publication by John Snow, the doctor, physician, and, unbeknownst to him, early epidemiologist. It contains his findings on Cholera and how it was spread, or, communicated. Up to the late 1850s the theory of disease contamination was one of miasma. To ensure disease was not spread, you would need to purify the air, rather than clean down surfaces, drink clean water and definitely not shake hands with any who is coughing, sneezing or looking blue.

Cholera was, and is, a terrible disease that can kill someone within hours. It is easily preventable by not using contaminated water, but this was not understood at the time. The disease was terrifying to societies across the world and in Britain there had been epidemics in 1832, ‘48 and ‘54.

A young woman of Vienna who died of cholera, depicted when healthy and four hours before death. From the Wellcome Library Collections.

Jon Snow promoted the theory that cholera was spread through contaminated water. During the 1830s to ‘50s he was not taken seriously and seen as someone on the fringe. Today, he is seen as a hero. The John Snow Society, made up of eminent epidemiologists, honours and promotes his work. Guided tours, books and plays have been produced about his work and his life. There is even a pub named after him.

The book, or as I call it, Modoc, is quite comprehensive. It includes his findings from Soho in September 1854, the infamous pump and famous Cholera Map he produced. Today, this is the most famous piece of his work, but it is not the most comprehensive or compelling. For some reason we focus on the story in Soho, probably because it is more concise, visual and adventurous. After all, we love adventure, not statistics. On the Wiki page to him, for example, over half of it is devoted to the Soho event. The landing page of the John Snow Society’s website has it there front and centre.

The Soho, Broad Street Map, within the book. Going by the sharpness of the creases, this one has hardly been looked at.

I sometimes drink in Soho, in the trendy bars. One time in a Spanish bar, sipping a dry iced sherry next to a bowl of Manzanilla olives, I took a quick look at the Cholera Map (on my phone) and saw that there were two cholera deaths in this place. It somehow gave a bit of gravitas to the evening.

But Soho was only the beginning for him. His major piece of work was the Grand Experiment, which he carried out after the devastating 1854 epidemic. He used statistics to prove his theory, linking cholera deaths in households, to the water company that supplied the water. It was a large and comprehensive piece of work using government records on cholera deaths, and walking up streets and knocking on people’s doors asking them about the water supply.

In Lambeth, there were two contrasting companies who were operating side by side. The Lambeth Water Company and the Vauxhall and Southwark Water Company. At that time, September 1854, Lambeth was taking its water from Surbiton, which was cleaner water from outside the tidal Thames. It was filtered onsite, piped to reservoirs and then onto the customers. The Vauxhall company on the other hand, was taking it straight out of the heavily polluted Thames at Battersea and piping it direct to their customers. If the occupants didn’t know about the water supply, ie which company was used, a salinity test could be used. Although, by simply looking at the colour of the water you could tell which company it came from.

From the Appendix. “The deaths of cholera registered in the four weeks ending 5th August 1854, together with the supply of water in the houses in which the fatal attacks took place, in all the sub-districts to which the water supply of either the Southwark and Vauxhall or the Lambeth Company extends”

Suffice to say, people were 14 times more likely to contract cholera if they drank the Vauxhall water. On March 5, 1855 Snow gave evidence to a Parliamentary committee chaired by Sir Benjamin Hall, on the 1854 Cholera epidemic. This is from Hansard:

162. [Mr. Wilkinson] “Did not you make particular inquiries at the houses which were supplied by two companies which take their supply of water from different places?”

Dr. Snow: “Yes; the one is supplied from Battersea Fields, near Vauxhall Bridge, and the other from Thames Ditton.”

163. “Was there a very marked difference between them?”

Dr. Snow: “There was. In the first four weeks of the epidemic the mortality was fourteen times as great amongst the customers of the Southwark and Vauxhall Company, getting their water in Battersea Fields as in the other, taking into account the number of houses supplied by each company.”

Although he had published data, produced maps, presented to Parliament, Snow’s work was not recognised for many years. It is difficult to change society and especially the establishment’s habits. In fact, his findings were not accepted until after his early death in 1858. He was only 45 when he died. His findings though, went on to establish an understanding of disease and the importance of clean water.

In history, much of the emphasis of cleaning up London and reducing disease has been given to Bazelgette and his sewers, but this was the real moment of change, Snow was the protagonist, and his work is where the real understanding on hygiene came from.

Today John Snow is seen as a hero, and when I was studying this piece of history for a project I was working on, he became a hero for me. He was unaccepted. Died before his work became realised. He had the gumption, stamina and resilience to stand up for what he had proved, with data and facts.

When I opened his book and it fell on the title page, I was stopped in my tracks. On the inside cover, is the stamp of the library of Metropolitan Water Board (MWB), Lambeth District. Always look on the inside covers for notes and stamps. It will tell you about more about the book than what’s printed inside. This was one is a second edition that was sent to the Lambeth Water Company. The Metropolitan Water Board was established in 1903 and absorbed the private water companies including Lambeth. I didn’t need to know this history of the MWB, because on the opposite page, is written:

Annotation on the inside cover reads,
Mr Secretary
of the Lambeth Water Company
with the Compliments
of the Author

How stock and assets get moved around from one organisation to another is quite interesting, but that wasn’t what stopped me in my tracks. It was the handwriting. Whose was it? Was it the hand of John Snow? Was I staring into the very genius that was him? Quite possibly. I do like to let my imagination run away, and I had a gut wrenching feeling it was. On balance, I thought, he may have had a clerk for his administration and maybe the handwriting is his. Snow was a doctor after all and had the fame of treating the royal family. How would you know, how would you find out if it was John Snow’s handwriting? By fortune, I found Snow’s signature on the Wikipedia page devoted to him. Look at the individual letters, especially the S and the T, and compare. It is his. This made me admire him even more. Personally writing on the inside covers and referring to himself in the third person.


Snow, J. On the Mode of Communication of Cholera, 2nd Edition, 1855.

Further reading

Steven Johnson. The Ghost Map: A Street, an Epidemic and the Hidden Power of Urban Networks. Penguin Books, 2008.


Wikipedia –

The Broad Street/Soho Map –

The John Snow Society –

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