Calculations: with the Principles and Data On which they are instituted: Relative to a Late Acts of Parliament, Intituled, An Act for raising and establishing a Fund for the Provision for the Widows and Children of the Ministers of the Church, &c.

First edition. Folio (44 x 28.5cm). 'Webster's favourite study had been mathematics, and he applied his knowledge in a philanthropic manner. In 1742 he laid before the general assembly a proposal for providing annuities for the widows of clergymen, basing his plan on actuarial calculations. To obtain information that would enable him to formulate his scheme, he put himself in communication with all the presbyteries in Scotland; and the tables of average longevity drawn up by him were so accurate that they have since formed the basis for similar calcualtions made by modern life insurance companies.'- DNB. pp. [10],5-16,[17-27],28-45,[1]. With the half-title. Presentation copy to Lord Sandys, Chancellor of the Exchequer in the Wilmington administration, and an advocate for government financial probity. Some occasional light foxing. An excellent copy in contemporary mottled calf, the boards with double-lined glt borders, rebacked in roan, hinges cracked & inner-hinges strengthened, but quite sound & tight. Vg. [Hanson 6210; DNB XX, 1025; Kress S.3786].…