As stated in the introduction to the Tables, they relate to 10,255 persons, as under—

And they embrace the experience of the first thirty-four years of the Society—reckoning, as was found most suitable, the first year's experience as the experience of the persons entering in the first year for one year from their respective entries, and so on. In this way it will be found that the experience does not include any of the persons entering in 1860, and none of the deaths in 1860 of persons who had been assured for more than a year from the time of payment of their annual premium in 1859. These deaths, and the entries of 1860, fall, according to the principle adopted, to be included in the experience of the thirty-fifth year of the Society.

It is to a Mr. George Barrett, of whom nothing besides is publicly known, that we are indebted for the principle of the Commutation Tables, and for the method of computing, by means of them, the values of benefits depending on the contingencies of human life. The method was first introduced to public notice, after it had been refused a place in the Transactions of the Royal Society, by Mr. Baily, in an Appendix to the second edition of his Doctrine of Life Annuities, published in 1813. Mr. Griffith Davies, in a work on life contingencies, published in 1825, by certain additions to the tables, and alterations in their structure, according to Professor De Morgan, “increased the utility and extended the power of the method to an extent of which the inventor had not the least idea.” Mr. Barrett's method was also briefly noticed in the Appendix to Mr. Babbage's Treatise on Life Assurance. The method, as improved by Mr. Davies, has since been treated, and a very large collection of tables adapted to it, for both one and two lives, has been given, by Mr. Jones, in his work on annuities, in the Library of Useful Knowledge. But by far the most valuable papers on the subject are two in the Companion to the Almanack, for 1840 and 1842, by Professor De Morgan, which contain the materials of many thousand formulae, applicable to almost every case that can occur. There is also some notice of the method in the article “Reversions,” in the Penny Cyclopædia, which article likewise is the production, we believe, of Professor De Morgan.

In the Assurance Magazine (Oct., 1860, and July, 1861) there have appeared two papers written by me to show in what respect the law of human mortality described by Mr. Gompertz in 1825 differs from the law described by me in 1832. In the same papers I have also shown in what respect the formula of Mr. Gompertz, , for the number living in terms of the mortality according to age, differs from my formula for the same purpose, which is , on putting instead of , as assumed by Mr. Gompertz.