The Twin marchant calculating machine

Calculating machines in general offer the following advantages over logartihms-increase of speed and scope of calculation, diminution of effort and of fear of msitakes, a lowering of the grade of skill required and, finally, the employment of the more sensitive natural values of the trigonometrical functions instead of the logarithmic values. The object of this pamphlet is to give a general introduction to the Twin Marchant calculating machine.

The elementary processes of addition, subtraction, multiplication and division are treated fully, and brief instructions on maintenance are given for instrument meachanics. This summary represents, apart from a few extensions of the fundamental processes, the full scope of the pamphlet. Details of the application of machine methods to the technical problems are omitted and may be found in the appropriate techincal pamphlet, notable in Artillery Training, Volume VI Pamphlet No.9 Computation.