Description

SHEPPARD’S PATENTED DOUBLE-SLIDE SLIDE RULE, English, c. 1880, signed for the maker “Stanley Great Turnstile Holborn London,” for the inventor “Fred’k. A. Sheppard Patentee No. 160,” and for the owner “Claude W. Atkinson.” Constructed of fine boxwood, 13″ (33 cm) overall, the rule has two two-sided slides running alongside each other. In the simple mode for volumetric calculations, the upper fixed scale “Length,” the two sliding scales (“Breadth” and “Thickness”), and the lower fixed scale “Cubic Content” all have identical logarithmic divisions. To find the volume of a rectangular parcel, for example, one sets up the three dimensions and sees the answer immediately. To the reverse of the sliders are scales of square roots and linear scales of numbers. One edge of the rule has an applied (later?) paper scale of sines. We note a discussion of the relative merits of Sheppard’s rule versus one of Dring and Fage, published in the 1883 English Mechanic and World of Science. An uncommon rule, in very fine condition throughout.