DataViz History: The Ghost Map: Building a Case and The Pump Handle

pump2Dr. John Snow is credited with taking bold action when he sensed that contaminated water from the public pump on Broad Street was the cause of deadly cholera during the 1854 outbreak in London. Here is what he wrote of his legendary action on September 7, 1854. [SOURCE]


“I had an interview with the Board of Guardians of St. James’s parish, on the evening of Thursday, 7th September, and represented the above circumstances to them. In consequence of what I said, the handle of the pump was removed on the following day.”

– John Snow in his 1855 book

So who was the parish Board of Guardians and why did they respond as they did to Dr. Snow’s recommendation?


In England, the parish is the fundamental tier of local government. Saint James’s parish encompassed the region serviced by the Broad Street pump. The Board of Guardians was elected by local citizens, but only those who owned property, thereby excluding many ordinary people. The voters were usually small tradesmen or shopkeepers who were concerned with public safety and order. The Board of Guardians was responsible, among other concerns, for maintaining public health, but relied on the advice of medical practitioners such as Dr. Snow.

There were several views of what happened on September 7, 1854 when Dr. John Snow spoke to the Board of Guardians at the Vestry Hall near his home and the impact thereafter on the Broad Street outbreak.


Snow’s good friend, Dr. Benjamin Richardson, wrote years later in 1858 of the September 7th meeting.

“When the Vestry (the term used for a committee of members elected to administer the temporal affairs of a parish) men were in solemn deliberation they were called to consider a new suggestion. A stranger had asked in a modest speech for a brief hearing. Dr. Snow, the stranger, was admitted, and in a few words explained his view of the ‘head and front of the offending’. He had fixed his attention on the Broad Street pump as the source and center of the calamity. He advised the removal of the pump handle as the grand prescription. The Vestry was incredulous but had the good sense to carry out the advice. The pump handle was removed and the plague was stayed. There arose, hereupon, much discussion among the learned… but it matters little for the plague was stayed.”


lankester1862In 1866, twelve years after the event, Dr. Edwin Lankester wrote further of the pump handle incident. He was a member of a local group that looked into the causes of the Broad Street outbreak, and was later to become the first medical officer of health for the St. James’s district (the area where the outbreak occurred.

“The Board of Guardians met to consult as to what ought to be done. Of that meeting, the late Dr. Snow demanded an audience. He was admitted and gave it as his opinion that the pump in Broad Street, and that pump alone, was the cause of all the pestilence. He was not believed — not a member of his own profession, not an individual in the parish believed that Snow was right. But the pump was closed nevertheless and the plague was stayed.”


At the time of the Broad Street pump outbreak, Reverend Henry Whitehead was a 29-year-old cleric at a church in the Broad Street area. He became interested in the epidemic and conducted his own investigation, independent of Dr. Snow.

The Index Case?

mother_infantRev. Whitehead may have discovered the origin of the Broad Street pump outbreak, which started on August 30, 1854. An infant girl at 40 Broad Street near the pump had an attack of diarrhea on August 28-29 that lead to her death on September 2nd. The mother described to Rev. Whitehead how, during her baby’s illness, she had steeped its soiled napkins in pails of water and had emptied some of these into the cesspool at the front of the house. Whitehead was struck by the dangerous proximity of the cesspool to the pump well and convinced a government engineer to examine the area. This examination revealed the seepage of fecal matter through the decayed brickwork of the 40broadstreet_smallcesspool to the well which was less than three feet away. If the child had died of cholera (which Whitehead supposed), then this likely would have been the index case that started the Broad Street pump outbreak.

For more on the index case at 40 Broad Street, click here.

Reverend Whitehead’s views on the effects of the Board of Guardians removing the pump handle were presented in 1867, thirteen years after the outbreak had occurred.

“It is commonly supposed and sometimes asserted even at meetings of Medical Societies that the Broad Street outbreak of cholera in 1854 was arrested in mid-career by the closing of the pump in that street. That this is a mistake is sufficiently shown by the following table which, though incomplete, proves that the outbreak had already reached its climax, and had been steadily on the decline for several days before the pump-handle was removed.”

The table he presented showed how the number of fatal cholera attacks had diminished from 142 on September 1st, to 14 on September 8th, the day on which the pump was closed. Thereafter the new fatal cholera cases fell to single figures and slowly dwindled away.

Whitehead went on in his presentation.

“I must not omit to mention that if the removal of the pump-handle had nothing to do with checking the outbreak which had already run its course, it had probably everything to do with preventing a new outbreak, for the father of the infant, who slept in the same kitchen, was attacked with cholera on the very day (September 8th) on which the pump-handle was removed. There can be no doubt that his discharges found their way into the cesspool and thence to the well. But, thanks to Dr. Snow, the handle was then gone.”


A month after the September 8th removal of the pump handle, Dr. Snow spoke of his views on cholera before the Medical Society of London on October 14, 1854. An account of his talk appeared in the October 21st issue of the The Lancet.


Was his action important, based on sound logic and understanding of the local situation? Or did John Snow and the Board of Guardians over-react?

Contemporary epidemiologists view removing the pump handle as appropriate, and honor Snow’s action to safeguard the public, even in the face of biological and epidemiological uncertainty.

Next: Myth-Making and Evolution of the Ghost Map


Brody H et al. The Pharos 62(1), 2-8, 1999.

Chave, SPW. Medical History 11(2), 92-109, 1958.

English MP. Victorian Values — The Live and Times of Dr. Edwin Lankester, 1990.

Rivett, G. The Development of the London Hospital System, 1986.

The Lancet 67, 339-41, 1854.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.