The Rev. H. Whitehead's report, like that of Dr. Snow, is a model of careful and extended observation and study, cautious generalizing and rigid verification. It is an excellent instance of inductive scientific inquiry by a layman in sanitation. Mr. Whitehead found the number of houses on Broad Street 49; the resident householders 35; the total number of resident inhabitants 896; the total number of deaths among these 90. Deaths among non-residents (workmen, etc.) belonging to the street, 28. Total deaths chargeable to this street alone, 118. Only 10 houses out of 49 were free from cholera. The dates of attack of the fatal cases resident in this single street were as follows: +------------+----------------+ |Date of | Number of | | Attack | Fatal Attacks| +------------+----------------+ |August 12 | 1 | |August 28 | 1 | |August 30 | 1 | |August 31 | 6 | |September 1 | 26 | |September 2 | 24 | |September 3 | 9 | |September 4 | 8 | |September 5 | 6 | |September 6 | 5 | |September 7 | 0 | |September 8 | 2 | |September 9 | 1 | +------------+----------------+ | | 90 | +------------+----------------+ Mr. Whitehead's detailed investigation was not made until the spring of 1855, but in spite of this fact it supplied most interesting and important confirmatory evidence of Dr. Snow's theory that the Broad Street well was the source of the epidemic. Mr. Whitehead, moreover, went further than Dr. Snow, and endeavored to find out how the well came to be infected, why its infectious condition was so limited, as it appeared to have been, and to answer various other questions which occurred in the course of his inquiry. As a result, he concluded that the well must have been most infected on August 31st, that for some reason unknown a partial purification began on September 2d, and thereafter proceeded rapidly. There was some evidence that on August 30th the water was much less infected than on the 31st, so that its dangerous condition was apparently temporary only. He further discovered that in the house No. 40 Broad Street, which was the nearest house to the well, there had been not only four fatal cases of cholera contemporaneous with the epidemic, but certain earlier cases of an obscure nature, which might have been cholera, and that dejecta from these had been thrown without disinfection into a cesspool very near the well. On his reporting these facts in April, 1855, to the main committee, Mr. J. York, secretary and surveyor to the committee, was instructed to survey the locality and examine the well, cesspool and drains at No. 40 Broad Street. Mr. York's report revealed a startling condition of affairs. The well was circular in section, 28 feet 10