Defects of Wood Slide Rule.
As the Slide Rule is an instrument used for various complicated calculations by the aid of its logarithmically graduated scales, it is needless to say that absolute accuracy of graduation is an essential point of the Rule. The body of Slide Rule has hitherto been made invariably of seasoned hardwood such as mahogany or boxwood, but, as the wood usually tends to warp partly or wholly even if to a slight degree on account of change of temperature and humidity, as a natural consequence the scales A. B. C. and D. suffer loss of exactness which is vital to the Slide Rule. This deficit is common to all wood slide rule and can not be avoided by any treatment.
Construction of Hemmi’s Slide Rule.
It has long been recognized by specialists that bamboo, which is one of Japan’s special products, if well seasoned, does not shrink or lengthen under any change of atmospheric temperature.
Hemmi’s Bamboo Slide Rule was indeed designed with this point in view. The body of the Rule is taken from mature bamboo which is well seasoned and freed from greasy matters. As is seen in the above section the upper and the lower scales are composed of two pieces and the slide is of four pieces of such bamboo, each piece being joined to the other with the solid part outside. The upper scale is connected with the lower by the celluloid sheet with narrow groove in the middle, and also by adjusting plate or thin aluminium. Thus it will be seen that the body of the Ruler is not of one solid piece, but consists of several pieces joined together with mechanical skill.
Characteristic features of Hemmi’s Bamboo Slide Rule.
(1) Accurate and non-shrinking.
The surface of the Rule is covered by perfectly seasoned celluloid sheet, and the upper scale is entirely separated from the lower by the adjusting plate. The ingenuity of construction by which equal balance is acquired, and the special nature of Bamboo, combined, remove the probability of warp, twisting, shrinking or lengthening under any climate or humidity. This feature is more remarkable with longer rules.
(2) Evenness and smoothness.
Bamboo Slide Rule does not absorb damp, so the slide moves always with ease.
Moving the slide just a little is just generally found difficult in case of Wood Slide Rule, but Hemmi’s Bamboo Slide Rule does entirely away with this difficulty, and the slide will move at your will, which Wood Slide Rule can not attain in countries like England and Japan where humidity is far more than average.
(3) Adjustment of Slide-groove.
If the movement of the slide is too stiff or too loose, draw is out, hold the upper scale with your right fingers and the lower scale with your left, pressing slightly inwards or outwards as the case may require, so that the width of the groove is adjusted to suit the slide.
(4) Distinctness and accuracy of graduation.
The Hemmi’s Bamboo Slide Rule is graduated by the machinery devised after our long year’s experience, and the accuracy and distinctness of graduation, as well as the superiority of construction of its stock, are what we believe can really be boast of.
Printed in Japan