It was the great epidemic of 1871-72 that brought out the change of age-incidence most concretely, just as it brought out, in contrast to the last great epidemic in 1837-40, the decline in the rural and the increase in the industrial centres. In the three years before the outburst of 1871 the deaths under five and over five were approaching an equality; in the epidemic itself the old ratios were suddenly reversed:

In the whole generation between 1840 and 1871, in which there was no great and general epidemic of smallpox, many had passed from childhood to adolescence and maturity without encountering the risk of it. When the epidemic of 1871 began, it found many in youth or mature years who had not been through the smallpox, and it attacked a certain proportion of them accordingly. The proportion above the age of five so attacked in 1871-72 was greater than it had been in this country since the beginning of the 18th century; indeed, as the information is not in statistical form for the earlier period, it may be asserted, and it may happen to be true, that it was greater than it had ever been in this country at any time. The reason for the large proportion of adult cases was the same in the rise of smallpox as in its decline, namely, that in the respective circumstances an epidemic found many who had not been through the disease in infancy or childhood. The same happened in those parts of the world where the epidemics of smallpox came at long intervals, during which many had passed from childhood to youth or mature age without once encountering the risk of smallpox.

Just as smallpox in its first great outbursts in the London of the Stuarts, or in its rare outbreaks in the American colonies in the 18th century, fell impartially upon children and adults, so in its last outbursts in the London of Victoria it fell upon persons at all ages. The notable thing is, not that smallpox should have of late been attacking adults, for that it has ever done except in times and places in which there were few or no adults who had not been through the disease in childhood; but that it should have ceased to so large an extent to attack infants and children. It has ceased to attack infants and children because other infective and non-infective diseases more appropriate to the modern conditions of the population are attacking them instead. These are measles and whooping-cough, scarlatina and diphtheria, infantile diarrhoea, and the more chronic after-effects of these. The annual death-rate from all diseases under the age of five has fluctuated somewhat per million living from 1837 to the present time, but it can hardly be said that it has fallen much or steadily[1179].

Keeping still to the epidemic of 1871-72, let us consider whether there was any natural or epidemiological reason for its cutting off a smaller ratio of infants and children in its whole mortality than that of 1837-40 did. There had been a most disastrous epidemic of scarlatina for three years just before, which had caused 21,912 deaths in 1868, 27,641 in 1869, and 32,543 in 1870, a total of 82,096 in three years, about two-thirds of which were under the age of five, or at the age-period which smallpox used to be fatal to almost exclusively and to be the greatest single epidemic scourge of. Even in the two smallpox years themselves the scarlatinal deaths were 18,567 and 11,922, of which the share that fell to children under five was one and a half times the deaths in that age-period from the co-existing smallpox. The three years of excessive scarlatina, before the epidemic of smallpox began, had removed large numbers of the class of infants and children who succumb to any infectious disease; if we cannot give the whole rationale of one infection dispossessing or anticipating another, we can at least understand that the earlier and more dominant infection takes off the likely subjects. What scarlatina did egregiously during the three years just before the great explosion of smallpox, it had been doing steadily (along with measles, &c.) throughout a whole generation since the last great sacrifice of infants and children by smallpox in 1837-40. But the fact that scarlatina had in great part dispossessed smallpox among the factors of mortality under the age of five, did not prevent the latter infection from attacking those of the higher ages who were susceptible of it and were at the same time unvexed by any other great epidemic malady proper to their time of life. If the epidemic of smallpox in 1871-72 had cut off as large a ratio under the age of five years as its immediate predecessor in 1837-40 did, its whole mortality would have been about 70,000 more than it actually was. But in no state of the population or of the public health can we suppose that three years of excessive mortality of children by one kind of contagion would be followed immediately by two years of equally special mortality at the same ages by contagion of another kind. It is not only epidemiological science that tells us this, but also common sense—est modus in rebus.

The saving of life by checking the prevalence of smallpox was a favourite rhetorical topic in the 18th century. Voltaire, La Condamine, Bernoulli, Watson, Haygarth and others, were fond of estimating how many thousands of lives might be saved in a year if inoculation were thoroughly carried out. Dr Lettsom, Sir Thomas Bernard and Mr James Neild, who were interested in prison reforms and in whatever else would reduce the prevalence of typhus, reckoned the possible saving of life under that head as almost equal to the possible saving from smallpox[1180]. For typhus there was no artificial means of restraint; it had to decline before natural causes, if it declined at all,—which, indeed, it has done. But no one at that time thought of keeping down smallpox except by the inoculation of itself or of cowpox. The economists and statisticians treated each of these artifices in its turn as a factor having a certain absolute value, which they might use like the a and b of a problem in algebra. This they did, of course, in deference to medical authority. What Bernoulli had worked out for the old inoculation, Duvillard did for the new, in his “Tables showing the Influence of Smallpox on the Mortality of each period of Life, and the Influence that such a preservative as Vaccine may have on the Population and on Longevity[1181].” Malthus fell into the conventional way of thinking when he assumed that smallpox alone among the epidemic checks of population was to be controlled artificially; but he introduced an important new consideration. “For my own part,” he wrote in 1803, “I feel not the slightest doubt, that if the introduction of the cowpox should extirpate the smallpox, and yet the number of marriages continue the same, we shall find a very perceptible difference in the increased mortality of some other diseases[1182].”

Five years after this was written, there came, in 1808, the disastrous epidemic of measles, which in Glasgow killed more infants in a few months than smallpox had ever done at its worst in the same city. In the winter of 1811-12 there was another severe epidemic of measles in Glasgow; and in 1813, Dr Watt, a leading physician of the place, and a man now famous in all countries for his vast labours as a bibliographer, gave to the world his statistical proof, from the Glasgow burial registers, of that law of substitution which Malthus had found necessary in his deduced principles.

The high ratio of measles and the low ratio of smallpox did not remain as Watt’s researches left them. When Cowan resumed the tabulation of figures from 1835 to 1839 he found the ratios of those two infantile infections almost equal, and the two together contributing to the whole mortality of Glasgow only a little more than half their joint share in the end of the 18th century. The substitution which Watt saw during a few years was only the most dramatic part of a general movement forwards of measles among the causes of infantile mortality. He supposed, as everyone did at that time, that smallpox was forcibly repressed, and that another infectious disease had seized the opportunity to become exuberant. The most relevant thing in the whole situation was urged by those who thought, with Jenner, that the doctrine of substitution had an “evil tendency” as detracting from the absolute value of the inoculation principle. In order to discredit Dr Watt altogether, they pointed out that his ratios of smallpox and measles took no account of the diminished death-rate of Glasgow by all diseases in the earlier years of the 19th century.

Great changes were proceeding in the old city, the Glasgow of ‘Rob Roy.’ The population which was reckoned at 45,889 in the year 1785, had increased to 66,578 in the year 1791, and thereafter, at a slower rate, to 83,769 in 1801 and to 100,749 in 1811. The first great increase after the American War meant overcrowding; but in a short time new suburbs spread over such an extent that, in the year 1798, more than half the burials were in the graveyards attached to chapels-of-ease and meeting-houses outside the original parishes. The modern expansion of Glasgow, like that of London and of all other large cities, has been an increase of area still more than an increase of numbers. The public health improved steadily, at all events until 1817, the improvement being shown first in the increasing number of infants that survived their second year. That rise in the probability of life corresponded to the substitution of measles for smallpox, and in part depended upon the ascendancy of the milder infection. Still more remarkable was the rise of scarlatina, which Dr Watt did not live to see; so little was made of it at the date of his writing that he found “scarlatina, typhus, &c., all comprehended under the same head.” The seeds of measles and scarlatina had long existed beside the seeds of smallpox, but the ascendancy of each of the two former had to wait events. Said Banquo to the witches who hailed Macbeth as king and himself as the sire of later kings:

“If you can look into the seeds of time,
And say which grain will grow, and which will not—”

The succession of reigning infections is the same problem. All we can say is that each new predominant type is somehow suited to the changed conditions. In the long period covered by this history we have seen much coming and going among the epidemic infections, in some cases a dramatic and abrupt entrance or exit, in other cases a gradual and unperceived substitution. Some of the greatest of those changes have fallen within the two hundred years since Sydenham kept notes of the prevalent epidemics of London. We are that posterity, or a generation of it, which he expected would have its own proper experiences of epidemics and at the same time would know all that had passed meanwhile—“posteris quibus integrum epidemicorum curriculum venientibus annis sibi invicem succedentium intueri dabitur.”

CHAPTER V.

Gaddesden, by some unaccountable stretch of similarity, coupled the sores or tubercular nodules on the legs of “pauperes vel consumptivi,” who were called “anglicé mesles,” with the spotted rash of the Arabian “morbilli”; and it was doubtless this haphazard bracketting of two unlike diseases that led in course of time to the name of mesles being disjoined from its original sense of the leprous and restricted to the second member of Gaddesden’s strangely assorted couple. In the time of Henry VIII. smallpox and mezils are familiarly named together just as variolae et morbilli are an inseparable pair in the treatises of the Arabistic writers. A still more singular usurpation by “mezils” or “maysilles” or “measles” is met with in the Elizabethan period. In the vocabulary of Levins, a schoolmaster who was also a medical graduate of Oxford, the word variolae is rendered by “ye maysilles,” while morbilli is omitted altogether among the Latin names and smallpox among the English; and in the English translation of Latin aphorisms appended to one of the works of William Clowes, surgeon to St Bartholomew’s Hospital, variolae is in like manner translated “measles” on every occasion. In the English dictionary by Baret, belonging to the same period, measles is defined as “a disease with many reddish spottes or speckles in the face and bodie, much like freckles in colour”—which seems to exclude the possibility of a pustular disease having been part of the Elizabethan notion of measles.

Notwithstanding this singular usage of the vocabularies and dictionaries, the name of smallpox occurs by itself in letters or other memorials of the Elizabethan period, having been doubtless correctly applied to the true pustular variola. In the short essay on smallpox by Kellwaye, appended to his book on the plague (1593), measles and smallpox are distinguished on the whole clearly, according to the definitions of Fracastori or other foreign writers of the 16th century. The association between measles and smallpox that survived longest was a peculiar and somewhat uncommon one; certain cases of smallpox, in which the pustules were wholly or partially represented by, or changed into, broad spots level with the skin, red or livid in colour, and in which haemorrhages occurred from the nose, lungs, bowels or kidneys, that is to say, cases of haemorrhagic smallpox, were apt to be called, from the time of James I. until as late as the case of Queen Mary in 1694, by the name of “smallpox and measles mingled.”

From the date of the annual bills of mortality by the Parish Clerks of London, the year 1629, it is improbable that there was any real confusion between smallpox and measles; there was certainly some ambiguity in the entry of measles long after, but that later confusion, especially in the second half of the 18th century, was with scarlatina[1184]. The entry of measles is in the bills from the first, apart from that of “flox and smallpox:”

In the great epidemic of smallpox in 1628, the year before the bills begin, Thomas Alured wrote to Sir John Coke that his house in London had been visited “once with the measles and twice with the smallpox, though I thank God we are now free; and I know not how many households have run the same hazard[1185].” In the year 1656, which has the highest total in the above table, two cases of measles are mentioned in a letter of 31st May: “Young Sir Charles Sedley is at this time very sick of a feaver and the meazells, of which Sir William dyed”—Charles Sedley being then in his seventeenth year[1186]. An instance parallel to that of 1628, of measles and smallpox co-existing in the same household, occurred in the royal palace at Whitehall in December, 1660. The princess of Orange, sister of the king, died of smallpox on the 23rd; on that day, or a day or two before, her sister the princess Henrietta, who had come from France on a visit with the queen-mother, Henrietta Maria, removed from Whitehall to St James’s, “for fear of infection.” After a few days she embarked on board the ‘London’ at Portsmouth to return to France, but the ship had to come to anchor again owing to the princess being attacked with “the measles.” Her illness, which delayed the sailing of the vessel until the 24th of January, 1661, is uniformly spoken of as the measles in the various letters which make mention of it[1187]. In that year, and in several of the next ten years, the measles deaths in London reached a considerable total:

The epidemic of 1670 is the subject of a description by Sydenham, the diagnostic points of which were doubtless those current at the time.

Sydenham’s description of Measles in London, 1670 and 1674.

Sydenham’s account of the epidemic of 1670 is full enough to leave no doubt that it was measles of the ordinary kind; the details, indeed, are as minute for all essential points as they would be in a modern text-book[1188]:

This epidemic, says Sydenham, began in January, and was almost ended in July, which agrees exactly with the rise and decline of measles deaths in the weekly bills of the Parish Clerks.

His account of the epidemic of 1674 is still more important to be set beside the figures in the bills; for the type, according to Sydenham, was anomalous, and the total of deaths entered by the Parish Clerks (795) is exceptionally large. Like the epidemic four years before, it began in January, came to a height about the vernal equinox, and was nearly over at the summer solstice[1189].

Weekly Deaths in London in the first six months of 1674. (Epidemic of Measles.)

1674

It will be seen that the highest weekly mortality from measles is only 95, in the week ending 17th May. But in that week the deaths from all causes reached the enormous total of 695, which was nearly three hundred above the weekly average of the time. This appears to have been the epidemic of measles which Morton declares to have destroyed three hundred in a week, a mode of reckoning which would claim for measles, directly or indirectly, the excess of mortality from all causes during the height of the epidemic[1190].

These high weekly mortalities in February, March, April and May are remarkable for the season of the year. Usually when the weekly figures reach six or seven hundred, it is in a hot autumn, and the cause is infantile diarrhoea, represented in the bills by the excessive number of deaths from “griping in the guts” and “convulsions;” more rarely, and then only for three or four weeks, correspondingly high figures are reached in a season of influenza. But in this case the epidemic measles is the only relevant thing. The measles deaths by themselves do by no means account for the enormous weekly totals; but two of the three columns of figures which help them, and indeed keep pace with the rise of the measles deaths, namely, “convulsions” and “teeth,” are infantile deaths obviously related to the prevailing epidemic; while the third column, “consumption,” which contributes most of all, did not in the London bills mean pulmonary consumption exclusively, but also the wasting or marasmus which followed or attended acute fevers in general, and was specially apt to follow or attend measles[1191].

Sydenham gives no indication that the spring of 1674 was unusually productive of pneumonia or pleurisy among adults; the winter, he says, was unusually warm, the weather in spring turning colder. But, as to the measles, he does say that the epidemic was anomalous or irregular; while both he and Morton refer the fatalities more especially to the sequelae of measles,—to the “suffocation” of infants and children by the bronchitis or peripneumonia, or to “angina,” as Morton says, meaning perhaps the same as in Scotland was understood by “closing” in infants. Measles itself was a milder disease than smallpox, according to the experience of all times; and yet, by its sequelae (bronchitis, capillary bronchitis and pneumonia, including what Morton calls “angina,” and excluding, for the present, whooping-cough), it raised the weekly mortalities of February, March, April and May, 1674, to far above the average. Sydenham said, with reference to the much milder epidemic of 1670, that these after-effects of measles “destroyed more than even smallpox itself” (quae [peripneumonia] plures jugulat quam aut variolae ipsae). We shall not correctly understand the part played by measles among the infective maladies of children unless we keep that grand character of it in mind—that its effects upon the mortality of infancy and childhood are only in part expressed by the deaths actually appearing under its name.

The London bills for 1674 afford us the opportunity of testing Sydenham’s paradox that measles, by its after-effects, destroyed more than smallpox itself. The epidemic of measles was nearly over in June; and immediately thereafter an epidemic of smallpox began (not of course from zero but from the usual level of the disease), which reached a maximum of 122 deaths in the week ending 20th October. The second half of the year was thus marked by a sharp outburst of smallpox, as the first half was marked by a sharp outburst of measles; and those two diseases were the only epidemic maladies that gave character to the respective seasons, each being in its proper season, according to Sydenham—measles in the spring, smallpox in the autumn. Although the measles deaths were only 795 for the whole year, the smallpox deaths being 2507, yet the former epidemic was attended by so great an excess of deaths under various other heads that the half of the year in which it fell was far more unhealthy than the succeeding half in which the smallpox mainly fell, the weekly average of the first six months having been 468 deaths, and of the second six months 349 deaths. The following table shows the weekly mortalities for the second half of the year; it will be observed that no column of figures keeps pace with the rise of the smallpox deaths, as three columns had kept pace with the rise of the measles deaths in the first six months of the year.

Weekly Deaths in London in the last six months of 1674. (Epidemic of Smallpox.)

1674

The total of deaths by smallpox for the year, 2507 was the highest since the bills began, and remained the highest until 1681. It is open to us to suppose that it would not have been so high but for the epidemic of measles preceding. The measles not only made the first half of the year far more deadly than the second, within which most of the smallpox fell, but its effects may have aided the high mortality of smallpox itself, according to the experience of later times that infants and young children recovering from measles in a greatly weakened condition fell an easier prey to smallpox coming after[1192].

Morton passes from the fatal epidemic of 1674 (or, as he says, 1672), with the remark that the malady had not been epidemic again in London from that time until the date of his writing, 1692-94, a period of nearly twenty years; and that is on the whole borne out by the London bills and by Sydenham’s records so far as they extend. From 1687 to 1700, inclusive, the London bills grouped the measles deaths along with the deaths from smallpox, under the heading, “Flox, Smallpox and Measles”; in 1701 the total of measles, 4 deaths, is given as a separate item in the same bracket with smallpox; and in 1702 the heading of “Measles,” is restored to the place in the alphabetical list which it had held, except for that unaccountable break, from the beginning of the published bills in 1629. The following are the annual totals from and including the great epidemic of 1674:

Thus for a good many years after the general prevalence of measles in 1674 the deaths from it in London averaged only about one and a half in the week, while in no year until 1705-6 is there an epidemic comparable to that of 1674. It is clear that the severe epidemics of measles came at first at very long intervals, and that the years between had a very moderate mortality from that disease.

Measles in the 18th century.

There is hardly a reference to be found to measles in medical or other writings until the annual accounts of the public health at Ripon, York, Plymouth, etc. in the third decade of the 18th century. The annual deaths from it in London, according to the bills, were as follows, from 1701, when the disease was restored to its separate place in the classification:

The high mortalities of 1705 and 1706 belonged to one continuous epidemic from October, 1705, to April, 1706 (Sir David Hamilton says that smallpox was common in London in July, 1705, but the deaths in the bills are not excessive). The epidemic followed a great prevalence of the autumnal diarrhoea of infants, so that it is probable the high mortality was due as much to a greater fatality of cases from the antecedent weakening, as to an unusual number of cases[1193]. The following were the weekly deaths in a population about one-sixth that of London now:

1705-1706

The unusually large mortalities from measles in 1718-19 and in 1733 were again associated with a “constitution” otherwise sickly. The epidemic in the latter year, from the middle of March to the end of July, which had a maximum of 47 deaths in each of the two middle weeks of May, followed close upon a severe influenza. Like the epidemic of 1674, it was attended by a high mortality from other causes, especially “convulsions” and “consumption”; and, as the bills had now begun to give the ages at death, it is no longer doubtful, or merely conjectural, that the great excess of deaths under these and other heads was really among infants, or that a rise in “consumption” at that time of the year meant an increase in the wasting diseases of infancy. This was a period when any epidemic malady among London children was sure to go hard with many of them, the period, namely, when spirit drinking, besides ruining the health of the parents, rendered them, in the opinion of the College of Physicians, “too often the cause of weak, feeble and distempered children[1194].”

The intervals between epidemics of measles in London having been so considerable as the table shows, it is not surprising to find but casual mention of the disease in the chronicles of Wintringham, Hillary, and Huxham for England, of Rogers, O’Connell and Rutty for Ireland, and of the Edinburgh annalists. Wintringham, of York, whose annals extend from 1715 to 1730, records an epidemic of measles in 1721, which began in April and lasted all the summer, being for the most part of a bad type, attended with continual cough and inflammation of the lungs. Hillary, of Ripon, enters measles in 1726, “very common but mild,” autumn and winter being the season of it. Wintringham briefly mentions the same epidemic. Huxham of Plymouth has an entry of measles in the first year of his annals, 1727, in the month of July, followed by whooping-cough in December. Wintringham again enters measles at York in 1730 in the company of smallpox. In the annual accounts of the disease at Edinburgh, for a series of years beginning with 1731, measles is first mentioned in 1735[1195]. The epidemic began in June and became universal in December: “The progress of these measles along the west road of England towards Edinburgh was very remarkable, for they could be traced from village to village; and it was singular that the first person in Edinburgh who was seized with them was a lady in childbed, who saw nobody but her nurse and a friend who lived in the house with her”—an argument, apparently, for the doctrine of an epidemic “morbillous” constitution of the air. Five years after, we obtain the mortality statistics of Edinburgh, in the two great years of scarcity, typhus fever and sicknesses of all kinds, the years 1740 and 1741: in those two years measles must have been as general as smallpox if it were half as mortal, for the deaths set down to it in each year are 110 and 112, as compared with 274 and 206 from the more usual infantile infection. In like manner the second year of the disastrous epidemic of typhus in 1741-42, had the highest total of measles deaths in London until the great epidemic of 1808. While the high mortality of that year was due to special causes, it is at the same time clear from the following table that measles had not yet become a steady or perennial cause of death to the infancy of the capital: