It is clear that Haygarth, who was well acquainted with epidemic smallpox and with inoculation, saw in this Gloucestershire idea something quite new as well as antecedently improbable. What the real novelty was will appear from the next historical reference to cowpox in an original work upon Morbid Poisons by Joseph Adams, a writer of the Hunterian school. All that Adams knew of the nature of cowpox previous to March, 1795, came from Cline, surgeon to St Thomas’s Hospital, who had been a fellow student of Jenner’s five and twenty years before, and kept up some correspondence with him. Adams is writing on the peculiar danger of ulceration and sloughing, or phagedaena, from transferring animal matters from one body to another, his last illustration having been the notorious phagedaenic ulceration of the gums, with rashes of the skin and constitutional effects so severe as to be fatal, which followed the transplantation of fresh teeth from one person to another in a number of cases about the year 1790 and led to the speedy abandonment of that unnatural practice[1073]. He proceeds to say, “Thus far we have only traced the poisonous effects of matter applied from one animal to another of the same class,” and then he brings in the illustration of cowpox to finish the chapter:

Jenner’s own essay on the cowpox, when it appeared at length in 1798, confirmed these statements as to the phagedaenic or corroding ulcerous character of the milkers’ sores, in his brief accounts of several cases, of which it will suffice to mention these two: William Stinchcomb, farm servant, had his left hand severely affected with several corroding ulcers, and a tumour of considerable size appeared in the axilla of that side; his right hand had only one small sore. A poor girl, unnamed, “produced an ulceration on her lip by frequently holding her finger to her mouth to cool the raging of a cowpox sore by blowing upon it[1075].” Inquiries made by Dr George Pearson in various other dairy counties of England brought out the same character of cowpox in milkers: the painful sores might be as large as a sixpenny piece, and might last a month or two, causing the milker to give up his work[1076].

As to the pap-pox itself, or cowpox in the cow, the most circumstantial account was obtained, a few months after Jenner’s first essay, by interrogating a veterinary surgeon or cow-doctor, one Clayton, who attended at most of the farms within ten miles of Gloucester:

No account of cowpox in the cow has ever been given which differs materially from that of this experienced Gloucester cow-doctor in 1798[1078]. Cowpox is not only a local disease, but it is peculiar to certain individuals of the species, namely cows in milk; in them it occurs on the teats, so that it was correctly known in Norfolk by the name of pap-pox. The common observation has been that one cow starts it, and that an infection is rubbed into the teats of others by the fingers of the milkers. The cow which develops this ulceration of the paps is usually either a heifer in her first milk, from which the calf has been taken away, or a cow in milk which has been bought in a market, with the udder “overstocked” or left distended for appearance sake, but as yet with no blemish of the paps. The cause of cowpox is the rough handling of a highly sensitive part, which was originally adapted only for the lips and tongue of the calf. Ceely, a correct observer in the Vale of Aylesbury, uses no exaggerated phrase when he speaks of “the merciless manipulations of the milkers.” Men milkers are well known to lack the delicate tact of women; and cowpox has been most common in the great dairying districts where men-milkers are employed. But in some animals cowpox may be produced even under gentler handling or with slighter provocation, of which I give a recent case from my notebook, taken during a visit to the country:

Jenner’s opinion that cowpox was a specific disease “coeval with the brute creation,” and that it had been the parent of the great historical smallpox of mankind, is not now received as correct. His other opinion, that cowpox was derived from the hocks of horses affected with “grease,” which held a central place in his original essay, especially in connexion with his doctrine of “true” and “spurious” cowpox, was rejected by most of his contemporaries, and is perhaps unsupported by anyone at the present time[1079].

In the title-page of his first essay, Dr Jenner called this singular malady of the cow’s paps by a new name—variolae vaccinae, or smallpox of the cow. Pearson, the earliest and most ardent of Jenner’s original supporters, and for several years thereafter a convinced vaccinist, at once took exception to the name variolae vaccinae “for the sake of precision of language and justness in thinking.” It is a palpable catachresis, says he, to designate what is called the cowpox by the denomination variolae vaccinae, because the cowpox is a specifically different distemper from the smallpox in essential particulars, namely, in the nature of its morbific poison and in its symptoms[1080].

That the term variolae vaccinae in Jenner’s title-page is used tropically can hardly be doubted; but it is not so easy to say which of the great classical tropes it is. It may be objected that “catachresis” is too general for the misuse of a word when that word is a scientific one and occurs in the leading title of a scientific book. Here we have the somewhat specific and purposeful use of a word in an unwonted sense, which, if it fall under any of the scholastic figures of speech, ought to be a figure more specifically defined than mere catachresis. In a matter so important as this one should find the exact figure if possible; but at the outset a difficulty arises, namely whether we should look for it in the usage of the rhetors, as Isocrates teaches, or in the usage of the logicians, as Aristotle lays down the definitions of tropes. If among the former class, the nearest is perhaps the hypocorisma, or attractive, agreeable name for something that is not so nice in itself. If among the latter, we shall hardly find a better than the metalepsis, which is a change more of mood than of meaning, namely the transition without proof from a supposition to an assertion. But in truth no single figure of the ancient teachers suits this modern instance. We require at least two. Metalepsis carries us so far, but synecdoche must supplement it. The term variolae vaccinae is a synecdoche in that it names the cause from the effect; it is a metalepsis in that it passes abruptly from the hypothetical mood to the categorical; and in respect that it does both at a stroke it is probably unique, and without precedent among the examples known to the ancients. Or again, leaving the graver figures, and translating the Latin name of Jenner’s title-page, one may try the figurative conversion of cowpox into smallpox by the standard of pure and legitimate paronomasia, of which there is a familiar English example in the conversion of a plant into an animal by the verbal play of horse-chestnut and chestnut horse in the minor premiss.

Some in more recent times, mistaking the figurative or rhetorical intention of Jenner, have understood his Latin name of cowpox as if there really were a smallpox of the cow (although not of the bull, nor of the steer, the maiden heifer or the calf of either sex). Not being able to find a smallpox of the cow in the natural way, they have thought to satisfy the legitimate requirements of proof by manufacturing it. Certain Germans of the Lower Rhine, where the cows ordinarily wear blankets, have wrapped the blankets taken from smallpox beds round the bodies of cows, after clipping the hair close; nothing was found to ensue in these interesting experiments except an occasional pimple which had probably been caused by the shears in the preliminary clipping. Others in England, France, America and India, have succeeded in raising a smallpox pustule at the point of puncture in the epidermis of the cow or in the more delicate transitional epithelium, the matter from which has produced smallpox in its turn[1081]. But these are academic exercises. The natural cowpox of the cow has been likened by none to the natural smallpox of man in a sustained comparison of all the anatomical and epidemiological particulars of each; nor, I am persuaded, will anyone ever attempt to draw out such a comparison. Variolae vaccinae as a name for cowpox was a figure of speech, and it is to misunderstand its original use to treat it as anything else.

The proof that cowpox had some power over smallpox consisted in trying to inoculate with the latter those who had been previously inoculated with the former. The accepted mode of testing the power of inoculated smallpox itself was to inoculate it again; at first the test for cowpox was to inoculate with smallpox, but after a few years the testing inoculation was done with cowpox itself. The effects of Suttonian inoculation with smallpox, as we have seen, were nearly always slight, and sometimes invisible (as in Watson’s practice at the Foundling Hospital). A previous inoculation with cowpox made them slighter still; but even with cowpox in the system, the pustules of smallpox rose where the matter had been inserted on the arm. It may be thought that there were only fine shades of difference between the effects of inoculation after cowpoxing and the effects of the same in a virgin soil; but some difference must have been perceived, for it was upon that, and upon nothing else, that the authority in favour of cowpox as a substitute for smallpox in inoculation was promptly established. The relationship between cowpox and smallpox was admitted by all to be in the nature of things “extraordinary,” as Jenner said, or a mystery, as others said; but as an empirical fact many believed it to be true, because the cowpoxed had less to show for the effects of inoculation with smallpox than if they had not been cowpoxed. Jenner himself is known to have made only two variolous tests. He used crude or watery matter from the local pustule of inoculated smallpox, and advised all his readers to do the same. In one of his two trials, a child Mary James had nearly the same effects from inoculation after cowpox that her mother and another child had from it without having been cowpoxed, namely the pustule or confluent group of pustules at the place of puncture, and the eruptive fever at the ninth day[1082].

In the earliest tests made independently of Jenner, five at Stonehouse[1083], near Stroud, and five at Stroud[1084], in the first months of 1799, the cowpoxed received smallpox afterwards by inoculation “in the usual slight manner.” In the practice at the Smallpox and Inoculation Hospital, London, in the spring and summer of 1799, many of the cowpoxed took smallpox by contagion from the atmosphere of the hospital, so that Woodville, after a period of perplexity, at length concluded that cowpox, while it was still active upon the arm, did not shut out the action of the smallpox virus in the constitution[1085].

The antecedent objections to cowpox, arising out of its non-variolous nature, were met by appealing to the results of experiments. The authority in favour of cowpox was speedily established on that ground, and has been continuous to the present time. The experimenters had to decide very nice points both in the way of observation and of reasoning. They had to appraise the margin of difference between the effects of Suttonian inoculation where cowpox had preceded and where it had not preceded. They had to allow for the first virus causing a swelling in the absorbent glands, which would obstruct the entrance of the second testing virus into the blood. They had to average the varying effects of Suttonian inoculation for its own sake, and the equally varying effects of it as the variolous test, and to find a broad difference between the two averages. Having decided that preceding cowpox infection did make a real and appreciable difference to the number of pustules resulting, at the spot or elsewhere, from the insertion of inoculated smallpox matter, or to the amount of fever, they had next to consider whether that degree of resistance by a cowpoxed person to inoculation were a good measure of his power to resist contagion reaching his vitals in the natural way. Their diligence and acumen may or may not have been equal to these things—it was a slack tide in medical science. Also they received little or no help from Dr Jenner himself, whose inventive genius was of the kind that is apt to leave the practical value, and even the theoretical probability, of the project to be tried by others. The inventor made interest with great personages—with the king, the duke of York, and the aristocracy of his county. His priority, and the merits of his project, were referred in 1802 to a Committee of the House of Commons, with Admiral Berkeley as chairman, which entered on its labours with a strong recommendation from the king, endorsed by Addington, the prime minister. They decided in favour of Dr Jenner’s claim for remuneration on all the issues, and on 2 June, 1802, the Committee of the whole House unanimously voted: “That it is the opinion of the Committee that a sum not exceeding £10,000 be granted to his Majesty to be paid as a remuneration to Dr Edward Jenner for promulgating the discovery of the Vaccine Inoculation, by which mode that dreadful malady the smallpox was prevented[1086].” On 29 July, 1807, a farther sum of £20,000 was voted to him; and on 8 June, 1808, a National Vaccine Establishment was appointed, at an annual cost of about £5,000.

Chronology of epidemics resumed from 1801.

In resuming the history of smallpox from the beginning of the present century, we come first to the deaths in the London Bills of Mortality, which are the only continuous figures. The bills of Parish Clerks’ Hall had failed, before they ceased, to include more than two-thirds, perhaps not much more than a half, of all the deaths in the capital. The great parishes of St Pancras and St Marylebone, which returned a somewhat excessive share of the deaths both from smallpox and from fever in the first two or three years of the Registration Act (1837-39), as well as the parishes of Chelsea and Kensington, were never included within the Bills; also much of the suburban extension on the other sides of London was never taken in. Meanwhile the area of the old Bills had actually become less populous owing to the displacement of dwelling houses by warehouses, workshops, counting houses, and the like, in the City, the Liberties and in certain out-parishes such as those bordering the Thames at the east end.

Still, the bills of mortality may be taken as showing on the whole fairly the proportion of smallpox deaths to other deaths, and the years of its greater outbursts.

Smallpox in the London Bills of Mortality, 1801-37.

The 18th century had ended with a severe epidemic of smallpox (2409 deaths) in the year 1800; and excepting in the year 1804, the deaths kept at a somewhat high level for ten years longer. The rise at the end of the last century corresponded to a time of distress and a severe epidemic of typhus fever. The fever declined after 1803, and remained for a dozen years at so low a level that Bateman, in his quarterly reports on the practice of the Carey Street Dispensary, expresses surprise that there should have been so little of it. The same writer, however, has occasion to remark upon the fatality of smallpox; twice he mentions large mortalities from it in courts adjoining Shoe Lane[1087]. According to the figures, also, smallpox declined less than fever. This means that, in the same circumstances, adult lives fared better than infancy and childhood. But, on the whole, smallpox shared with fever the advantageous conditions for health which obtained in all parts of the kingdom (in Ireland as well as in Britain) from the decline of the epidemics of 1799-1803 until the rise of the next epidemics in 1816-19. This period of comparative freedom from smallpox and fever corresponded to the second period of the great French War from its resumption after the failure of the Peace of Amiens until its termination with the Peace of Paris. It may seem surprising that this should have been a time of comparatively good public health in Great Britain and Ireland, inasmuch as it was a time of dear food and heavy taxes. The amount of typhus or relapsing fever is the best test; and those diseases, by all accounts, were at a lower level in all parts of the United Kingdom from 1804 to 1817 than they had been for many years before or than they were for many years after. Again, if precedents count for anything, the same kind of lull in smallpox and fever together is shown in the London bills during the war of the Allies against Louis XIV., and during the Seven Years War.

In Glasgow the decline of smallpox deaths for a few years in the 19th century was perhaps more marked than elsewhere because it was a decline from an excessively high level in the end of the 18th century.

Glasgow Mortalities, 1801-12.

Here it is not until 1805 that a marked fall in the smallpox deaths takes place. In Norwich there was a clear interval from the last severe period in the end of the 18th century, until the year 1805, when smallpox, “after being for a time almost extinct,” became prevalent again. At the Whitehaven Dispensary, the contrast between the last years of the 18th century and first years of the 19th is not striking[1088]:

Smallpox at Whitehaven Dispensary.

Carlisle, which used to share in smallpox as much as Whitehaven, seems to have been almost wholly free from it in the first twelve years of the century: at least Dr Heysham, who was no longer statistical, “had reason to believe” that no person died there of smallpox from the autumn of 1800 (when cowpox inoculation was introduced) until November, 1812[1089].

The Newcastle Dispensary, like that of Whitehaven, treated a small fraction of all the cases of smallpox in the town; but it continued to have a fair average of cases and deaths after the century was turned:

Smallpox cases attended from Newcastle Dispensary.

Most places continued to have their periodical epidemics of smallpox as before, although both measles and scarlatina were becoming more and more its rivals. Boston, Lincolnshire, had its sexennial epidemic in 1802 with thirty-three deaths. Besides the year 1805, there were two periods in which smallpox was somewhat general, 1807-9 and 1811-13. At Norwich from 1807 to the end of 1809 the bills of mortality showed 203 deaths from smallpox[1090]. In 1808 we happen to hear of it also at Sherborne, in Dorset, at Ringwood, in Hampshire, at Cheltenham, at Cambridge and at Edinburgh, although the great epidemic malady of children in that year was measles[1091]. Lettsom wrote on 25 January, 1808: “The smallpox (infanticides) and measles have been prevalent and fatal. The coffins for the parish poor in England for the smallpox deaths alone have cost £10,000[1092].”

In 1811 it began to be somewhat general again, and rose in London to a considerable epidemic in 1812, the deaths in summer rising to sixty in a week[1093]. A village epidemic of 46 cases and 7 deaths is reported from North Queensferry, near Edinburgh, from 14 December, 1811 to 7 March, 1812[1094]. At Norwich from 10 February to 3 September, 1813, there were 65 deaths[1095]. The rise from 1811 to 1813 coincided with an increase of fever, the winter of 1811-12 having been a time of dearth and depressed trade, especially in the manufacturing districts. After that came a notable lull both in fever and smallpox, which was at length broken by the epidemics of each in 1817 in Ireland, Scotland and England, coincidently with the depression of trade and dislocation of commerce that began everywhere as soon as the great war was over.

The Smallpox Epidemic of 1817-19.

The same things that favoured the prevalence of typhus and relapsing fever in times of distress, favoured also the rise of smallpox to the height of an epidemic. Hence the greater epidemics of smallpox in the first half of the 19th century coincided somewhat closely with epidemics of relapsing or typhus fever,—in 1817-19, in 1825-27, in 1837-40, and in 1847-49. That which fever was to the adolescents and adults in times of distress, the same was smallpox to the infants and young children. The young children of a family did, indeed, take fever sometimes as well as the parents or the young persons in it; but the children seldom died of it. They died of smallpox (or of measles or whooping cough or the like), perhaps all the more readily that they would have been weakened by the fever, and by the want of food and comforts which attended it. Thus, while fever and smallpox went somewhat closely hand in hand during times of distress, it was the adolescents and adults that died of fever, the infants and young children that died of smallpox. The following table, compiled from the reports of the Whitehaven Dispensary from 1783 to 1800, will show how many children survived attacks of continued fever in comparison with their elders[1096]:

Continued Fever at Whitehaven Dispensary, 1783-1800.

The deaths from smallpox are found nearly always to be high when the deaths from fever are high. The correspondence, however, is not always exact to months or quarters, or half-years; for it is not unusual in the London weekly bills to find a run of weeks with high deaths from smallpox just before or after a run of weeks with high deaths from fever. The domestic circumstances which spread the contagion of fever were such as might be expected to spread the contagion of smallpox, namely, the pawning of clothes, bedding and the like, on a vast scale in times of scarcity, the crowding of many in single rooms or in one bed, the wandering of men and women, attended by their children, in search of work, the exposure of children in the smallpox so as to extort alms. All these things were common in Ireland, Scotland and England during the long periods of depressed trade, alternating with periods of speculation and expansion, for which the generation following the Peace of Paris was remarkable. We hear far more of the fever than of the smallpox, because the former touched the lives of breadwinners, while the latter was often regarded as a matter of course[1097]. Thus, in the Irish famine of 1817-18, it is possible to estimate the prevalence of dysentery, relapsing fever and typhus fever by the aid of various records, including two treatises and the reports of a Parliamentary Committee. There are also two or three brief references to smallpox; but no one would have supposed that smallpox caused actually more deaths than fever itself, as in the following returns of burials in the Cathedral churchyard of Armagh, from 1st May to 25th December, 1818[1098]:

—the total of 463 being twice or thrice the numbers for the corresponding months of non-epidemic years. Whether there was as much smallpox in other provinces of Ireland as in Ulster, does not appear; but the following relating to Strabane and Londonderry will serve to prove that Armagh was not exceptional in the north of Ireland. In and around Strabane, smallpox began to spread in May, 1817, having been hardly known in the neighbourhood for years before; it was often confluent and was “fatal to hundreds” of children[1099]. The same severity of the epidemic is reported also from the county of Derry in 1817: “Cases of smallpox appeared in greater numbers than I had ever before witnessed, even previous to the valuable discovery of Jenner[1100].”

The vagrancy of the Irish peasants, not only cottiers but also many small farmers, began in Ulster in the end of the year 1816, after a wet autumn which ruined the crops; and it is probable that the contagion of smallpox began to be spread among their children about the same time. Whether a migration set in to England and Scotland at that time is not clear. It appears, indeed, that the first of the epidemic in England, in Whitehaven, Ulverston, and other places which were in direct communication with the North of Ireland, was at least as early as, and perhaps earlier than, the outbreak of the malady in that country. The whole of the United Kingdom was suffering in 1816 from depression of trade, and many of the labouring class were tramping from place to place in search of work. The following is the account of smallpox being brought to Ulverston[1101]: