GB190703685A - Improvements in and relating to Calculating and the like Devices. - Google Patents

Abstract

3685. Pugh, J. V. Feb. 14. Calculating-apparatus.-Relates to arrangements of the slide-rule type in which one or more logarithmic scales are divided into equal parts arranged side by side in order to secure a long and open scale. The logarithmic scale a, Fig. 1, divided into twenty equal parts, is connected by parallel links b, b to a member c, which is in turn connected to a base plate d by parallel links e, e. A pointer plate f is rigidly secured to the base-plate d along an edge h, and carries two pivoted arms i, jointed at k, and provided at their ends with indicating- marks m. To use the device, the pointer plate is conveniently placed with regard to the scale, and the indicating-marks m are set as required. The pointer plate is then displaced relatively to the scale by means of the parallel motion, the relative position of the indicating-marks remaining unaltered. The parts of the apparatus that pass in front of the scale are preferably constructed of celluloid. Various modifications are described. Thus, only one jointed arm i may be employed, a second indicating-mark being provided on the pointer plate itself ; or the pointer plate may carry several indicating-marks or pointers. A special scale may be used in certain calculations, when the ordinary scale cannot be employed owing to one of the pointers passing off it, consisting of a fundamental logarithmic scale divided into ten equal lengths, which are arranged so as to form a rectangle. The fundamental scale is then repeated to the right, and the whole scale so formed is duplicated. This arrangement may be varied in different ways. Further modifications consist in employing the usual uniform scale in conjunction with the logarithmic scale, to enable logarithms and antilogarithms to be formed. The parallel motion shown in Fig. 1 may be omitted by using the ruled transparent pointer plate n, Fig. 4, with one or more jointed arms i; or a metal frame r, Fig. 5, may be employed having its inner edge s bevelled, and provided with four indicating-marks t corresponding with the unity points of the scale.