As concerns Watt, we have the advantage of some notes upon his “remarkable treatise” by Dr. William Farr in the Thirtieth Annual Report of the Registrar-General, 1869. Having given an abstract of Watt’s results, Dr. Farr observes of his discovery of displaced and replaced mortality—
This is an important point in pathology; and it must be admitted that although there were defects in his data, Dr. Watt succeeds in showing (1) that Smallpox was one of the greatest causes of death in Glasgow down to the year 1800, (2) that the deaths by Smallpox were reduced to a fifth of their original number by Vaccination,[270] and (3) that the children died in nearly the same numbers as before, but of other forms of disease.
Glasgow has always been famous for statistics, and these unfortunately show an increase of the mortality of children. Thus in the five years 1821-25 the mortality of boys under five years of age was 8·08; in 1831-35 it was 9·78. In the year 1865 the mortality of boys in Glasgow was 11·48, of girls, 10·36. These recent returns confirm the principle. Smallpox is no longer so fatal as it was before Vaccination was introduced; in Glasgow it caused in the year 1864 no longer 20 but 2 in 100 deaths—only 180 in 6054 deaths, that is 3 per cent. of the deaths under five years of age; yet the mortality of children is certainly as high, probably higher, than it was in the last 10 years of the last century.
Compulsory Vaccination in England has reduced further the fatality of Smallpox, but since 1853 other diseases have so prevailed as to counter-balance the gain under this head. The mortality of children has not declined in a corresponding degree.
With confirmation under such authority, it is needless to enforce the validity and importance of Watt’s discovery. Dr. Farr is pleased to ascribe the subsidence of smallpox alike in England and Glasgow to vaccination, but he makes no effort to prove his case: indeed the effort might have led him to recognise his mistake. Referring to scarlet-fever, he shows how from a mild it has become a severe affliction—
Sydenham (d. 1689) describes simple Scarlatina distinctly: he does not refer to the throat affections, and says the patient can only die by the doctor’s default. Joseph Frank describes the disease as now the most dreadful scourge in Europe.
If then scarlet fever has of itself acquired this terrible intensity and predominance, why should it be thought incredible that smallpox of itself should undergo correspondent mitigation and diminution? Or, is it to be argued that vaccination has extinguished smallpox to revive as scarlet fever?
Dr. Farr proceeds to observe—
It is singular that Dr. Watt, evidently a practitioner of great sagacity, does not at all advert to the wretched sanitary condition in which the increasing population of Glasgow lived at the time he was writing.
It is the observation of Dr. Farr that is singular. At the time when Watt wrote there was no clear conception of the relation of condition to disease. Jenner was always writing about smallpox, yet there is not a hint in any of his papers as to its development in filth and stench. His own residence was a pesthouse, but it never entered into his head to ask, Why? Let us avoid anachronism. Those whose memory or reading extends to the cholera epidemic of 1831-32 will know, that it was regarded as an inscrutable visitation toward which humble submission was the proper attitude. A letter of Collins, the artist, to the Rev. R. A. Thorpe, 26th November, 1831, correctly expresses the common feeling. Referring to the Cholera and the Reform Bill, he says—