Smallwood calculator instructions

From the Grover Collection...

Four pages of fragile, slightly-bug-eaten operating instructions from a gorgeous Pascaline-style calculator I have. These instructions offer a great insight into the variety of different operations possible on a device that looks deceptively simple at first glance. The Smallwood adds numbers like most other Pascaline-type calculators and the sum appears in a row of "answer" windows. The subtraction operation is unusual for avoiding the "answer" windows entirely and instead using a secondary indicator on the rotating dials themselves. The passages on "correcting errors," "guards against interruptions," and "to tabulate two items at the same time" highlight some of less-obvious features of this model. The instructions for multiplying and dividing on the Smallwood are particularly interesting since these Pascaline calculators are often thought of as only "adding machines."

Click for high resolution JPGs of the instruction images: