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Page:Popular Science Monthly Volume 19.djvu/506

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calculations. The large and fluctuating population of a city like London, with its extremes of social conditions, could not be deemed a fair exponent of the value of healthy lives of the whole country. Dr. Price set to work to collect data from which trustworthy tables might be computed. He constructed quite a number of them, among which, one based on thirty years' mortality of Norwich, and another on ten years' observation at Chester, attracted considerable notice. He also applied such French, Dutch, and Swedish statistics as were available. But most important of all, and the one on which his fame chiefly rests, was the Northampton table, taken from thirty years' mortality observations of the town of Northampton. At the time of its publication, Dr. Price's numerous works had become widely known and his reputation was well established. In 1780 the Equitable Society, which had commenced with Dodson's London tables, concluded to adopt the Northampton table, and Dr. Price became the Society's consulting actuary. The directors generally followed his suggestions, and within a year he made 20,000 computations for them. The Society, now basing the reserves on the Northampton table, which showed a lower rate of mortality than Dodson's, found the surplus to accumulate rapidly, and large and frequent dividend additions were made to the old policies. With the reduction of the premiums the business increased steadily, and numbers of new companies were started in competition, whose fate we need not follow. Life insurance had become a practical system, established on a scientific basis.

The directors of the Equitable Society were intelligent and enterprising but very careful men. They had selected the Northampton table, from the different new tables presented, because among these it showed the highest rate of mortality. It proved to be based on a peculiar error of reasoning. An enumeration of the whole population could not be obtained, and the parish registers only gave a record of the christenings and deaths. But the town contained great numbers of Baptists, who repudiate infant baptism; and Dr. Price overlooked the fact that births and christenings were not identical, and assumed a much higher proportion of deaths to births than had actually occurred. The Northampton table came into general use, however, and the English Government, that had adopted it as a basis for annuity values, lost about £2,000,000 before its inaccuracy was discovered.

The next step of importance was the publication of a new mortality table, known as the Carlisle table, by an eminent actuary, Mr. Joshua Milne, in 1816. It was deduced from data obtained from the town of Carlisle, a very healthy and prosperous place, growing both by immigration and natural increase. During the eight years from 1779 to 1787 the population had risen from 7,077 to 8,677 inhabitants, being just 1,000, and the deaths recorded were 1,840. While the number under observation was very small, the advantage of having enumerations of the whole population was considerable. For the first