The Foundling Hospital was an ideal testing ground for new medical ideas & methods. The children all followed the same diet and regime, meaning that there were very few variable factors.
This gave doctors a unique opportunity for controlled studies, and Sir William Watson, a physician at the Hospital from 1767 until his death in 1787, took advantage of this to test different methods of smallpox inoculation in one of the first controlled clinical trials.
He was interested in perfecting the procedure of inoculation, and conducted carefully-documented experiments to find the best method. Inoculation involves taking some fluid or pus from someone infected and then pressing it into a scratch in the skin of a healthy person, provoking a mild outbreak of the disease. This outbreak is generally much less serious than if they were to contract it naturally.
Watson tested dozens of foundling children who were being inoculated in the off-site infirmaries to determine the best source of smallpox fluid. There was no consensus at the time and he wanted to find out whether fluid from an early pustule or a more mature lesion would provoke a milder outbreak of the disease in the inoculated patient.
He also tested the efficacy of common treatments of the time to prepare patients for inoculation: which included the use of mercury, jalap, rose syrup and senna (these last three being mild laxatives).
Watson conducted three experiments: one using fluid from an early smallpox lesion; another from a mature lesion; and the last from a late lesion. In each experiment, the children were inoculated at the same time and place, and with the same material. The only difference was the other general medical treatment they might have received. Watson’s systematic research had much in common with modern clinical trials.
To assess the effects of the different procedures he, or rather the infirmary nurses, counted the number of pustules on each child. In the end none of the laxative treatments was shown to be especially useful, although he noted that the use of mercury along with a laxative had less of an effect because the mercury stayed in the body for less time.
The mildness of the outbreak caused by inoculation in fact depends on the mildness of the strain of smallpox which is used. There were about seventeen strains of smallpox around in Watson’s London, split into two groups – variola major and variola minor (the latter being much milder). There is some evidence that the strains present from 1750 to 1850 were milder than those before and after.
Watson’s work laid the groundwork for later advances in inoculation, as well as in the development of controlled trials. The Foundling Hospital was his laboratory.
Visit the Foundling Museum’s current exhibition, The Generous Georgian: Dr Richard Mead, which highlights the contribution of an eminent physician, collector and patron to the Foundling Hospital. Find out about Mead’s pioneering role in establishing state-of-the-art medical treatment at the Hospital, including the inoculation of the foundlings against smallpox.
My next post will look at a mysterious cave that Dr Mead visited on his tour of Italy, which prompted his deep interest in poisons.
 For more information on Watson’s experiments, go to http://www.jameslindlibrary.org/illustrating/articles/william-watsons-use-of-controlled-clinical-experiments-in-1767