Such was the experiment by which Jurin “confirmed the practice of inoculation.” As for his authority, it was doubtless considerable; but it was more as a follower of the Newtonian mathematics than as a pathologist or physician, and most of all as one of the secretaries of the Royal Society in the last years of Newton’s presidency, that he spoke with authority[904]. His influence, such as it was, availed little. The practice of inoculation fell into total disuse in England after a few years’ trial, so that in 1728 Jurin himself was prepared to see it “exploded.”
The principal reason of inoculation having been tried upon decreasing numbers in England after the first year or two, and of its having been dropped absolutely for a time, was the death of some persons of good family, both adults and children—a sacrifice of life which could not but seem gratuitous. Those deaths were not from the fulness of the eruption but from anomalous effects. When inoculation began in London in 1721, it was according to the Greek method of inserting a minute quantity of matter at two or more places. In the case of the Newgate felons, Maitland had reason to do the inoculations over again after three days, being dissatisfied with the appearance of the original punctures. They are admitted to have had a slight disease (the man who had most had only some sixty pustules on his whole body), so that Dr Wagstaffe, who went to see them, said in his letter to Dr Freind: “Upon the whole, Sir, in the cases mentioned, there was nothing like the smallpox, either in symptoms, appearances, advance of the pustules, or the course of the distemper.” Many of the other early cases had likewise a slight eruption; when numbers are given, the pocks are “not more than eleven to eighteen” (as in Maitland’s case of Prince Frederick at Hanover in 1724), or “not above twenty in all upon her” (as in Maitland’s case of a child near Hertford, in 1721). Of the first six charity children inoculated, one had no eruption; of the next five, three had no smallpox from inoculation. The cases that died after inoculation during the first seven years of the practice—seventeen in England and Scotland and two in Dublin, most of them children—owed the fatal result for the most part to some peculiar prostration or lowered vitality, in two cases actually to pyaemia, the eruption being kept back altogether or but feebly thrown out[905]. This was the danger of arbitrarily procuring the smallpox which Dr Schultz remarked upon in 1677, with reference to the Polish practice of “buying” the disease; most, if not all the cases known to him, although they may have had few pocks, yet fell into more serious illness (gravius reliquis decumbant). The risk of arbitrarily forcing infection upon a child at a time when it might not be ready for it, or in a position to deal with it in its blood, was afterwards recognized, and was provided against in the long and tedious preparation which the subject for inoculation had to undergo.
While those in England who followed Maitland in inoculating after the Greek fashion produced for the most part an infinitesimal number of pustules or watery pimples, there were others at a distance from London who inoculated by a method of their own and gave their patients a more real smallpox. The chief of these were Dr Thomas Nettleton of Halifax, and Dr Zabdiel Boylston, of Boston, New England[906]. Nettleton made a long incision through the whole thickness of the skin of one arm and of the opposite leg, and laid therein a small piece of cotton soaked in smallpox matter, which he secured in the wound with a plaister for twenty-four hours. Boylston says: “The Turkey way of scarifying and applying the nutshell &c., I soon left off, and made an incision through the true skin,” the rest also of his procedure being the same as Nettleton’s. And just as those two inoculators devised for themselves a more real method of giving the smallpox by insertion, taking means to ensure the absorption of the matter into the blood, so they procured in many cases, although not in all, an eruption of pustules on the skin which came near to being the same as that of natural smallpox of the average discrete type.
In the Boston practice, “the number of the pustules is not alike in all; in some they are very few; in others they amount to an hundred; yea in many they amount unto several hundreds, frequently unto more than what the accounts from the Levant say is usual there[907].” Nettleton’s account, which was printed in the same number of the Philosophical Transactions as that from New England, says of the pustules on the skin at large: “The number was very different: in some not above ten or twenty, most frequently from fifty to two hundred; and some have had more than could well be numbered, but never of the confluent sort.... They commonly come out very round and florid, and many times rose as large as any I have observed of the natural sort, going off with a yellow crust or scab as usual[908].”
The smallpox procured by inoculation in these English and American trials was thus a more real form of that disease than at Constantinople; compared with the number of pustules given by Timoni and Pylarini, the Boston and Halifax numbers are multiplied ten times.
Nettleton thus expressed his belief that inoculated smallpox saved from the natural disease, at the same time grounding that belief on the reality or substantial nature of the artificial disease:
“Some of those who have been inoculated, that are grown up, have afterwards attended others in the smallpox, and it has often happen’d that in families where some children have been inoculated, others have been afterwards seized in the natural way, and they have lain together in the same bed all the time; but we have not yet found that ever any had the distemper twice; neither is there any reason to suppose it possible, there being no difference that can be observed betwixt the natural and artificial sort, but only that in the latter the pustules are fewer in number, and all the rest of the symptoms are in the same proportion more favourable[909].”
Nettleton returned to the question of the reality of inoculated smallpox, which is the root of the whole matter, in his second letter, to Jurin[910]: “The question whether the distemper raised by inoculation is really the smallpox is not so much disputed now as it was at first.... There is usually no manner of difference to be observed betwixt the one sort and the other, when the number of pustules is nearly the same; but in both there are almost infinite degrees of the distemper according to the difference of that number. All the variation that can be perceived of the ingrafted smallpox from the natural is, that in the former the pustules are commonly fewer in number, and all the rest of the symptoms are in the same proportion more favourable. They exactly resemble what we call the distinct sort.... It will follow as a corollary, that those who have been inoculated are in no more danger of receiving the distemper again than those who have had it in the ordinary way. And this is also thus far confirmed by experience.”
It does not appear that Nettleton based so much upon the subsequent experience as upon the antecedent probability. Thus he says of some cases:
“These had the eruptions so imperfect as to leave me a little in doubt, but two of these have since been sufficiently try’d by being constantly with those who had the smallpox, without receiving any infection; which makes me inclined to believe they will always be secure from any danger. As to all the rest, neither I nor anybody else who saw them did in the least question that they had the true smallpox.”