GB190726929A - An Improved Calculator. - Google Patents

Abstract

26,929. Tyler, F. W. Dec. 5. Calculating - apparatus. -Apparatus which is intended chiefly for the computation of the amounts of insurance premiums payable for odd periods of time, but which may be used also for determining the number of days and weeks between two given dates, the dates of expiry of sums forming part of annual payments, percentages, and fractions of sums of money, consists of a graduated disk a, provided with a thumbpiece a<1> and rotatable upon a pivot b within a fixed annular ring f, and a pointer g. Starting from the centre, the disk a is inscribed with nineteen concentric circles representing shillings from one to nineteen, each circle being divided into parts equal in number to the shillings it represents. Five similarly-graduated concentric circles follow, representing shillings from twenty to a hundred, as shown. Finally, there are circles indicating the proportionate amounts of a premium of ú100 for every date in a year, and the number of weeks and days in the year. The fixed circle f is graduated so as to indicate the days and months of the year, and the pointer g is marked so as to indicate the amount of annual premiums up to ú5 on the disk a. To calculate, say, the amount payable upon an annual premium of ú5 between January 1 and April 30, the disk a is turned so that the zero division upon its outermost circle is brought into coincidence with the graduation representing the former date upon the outer fixed circle f. The pointer g is then turned to the latter date, and the point at which it cuts the 100s. or ú5 circle gives the amount required.