early slide rule
Date: 1689
Inventory Number: DW0960
Classification: Slide Rule
Maker: S.A.C. (ca. 1650 - 1700) Dimensions:3.9 × 23.1 × 1.4 cm (1 9/16 × 9 1/8 × 9/16 in.)
DescriptionRectangular boxwood rule composed of two slides, which slide apart. Each slide is attached to one of the brass end frames: the top slide, to the left frame; the bottom slide, to the right frame.
The face of the rule is printed with three scales. Along the top edge of the top slide is a scale in inches, graduated into tenths and with values descending from 8 to 0. Printed along the bottom edge of the top slide are one full and one partial logarithmic scales, with values ascending from 3 to 10, then from 1 to 10. Along the top edge of the bottom slide is a logarithmic scale "N" with values ascending from 1 to 40. Below each of the values on this scale are between one and three additional values, arranged into a table with four rows. The top row of the table has values descending from 89 to 50. The second row has values ascending from 0.2 to 5.8. The third row has values descending from 99 to 86. The third row of the table begins at the bottom scale's mark for 5; below each mark for 2, 3, and 4 is an X. Between the second and third rows of the table on the far left is the letter "T".
The back of the rule is also printed with three scales. Along the top edge of the top slide is a scale in inches, graduated into tenths and with values ascending from 8 to 16. Along the bottom edge of the top slide is a scale labeled "N", composed of one full and one partial logarithmic scales, with values ascending from 3 to 10, then from 1 to 10. Printed along the top edge of the bottom slide are one full and one partial logarithmic scales, with values ascending from 1 to 10, then from 1 to 3. Below this are tables for trigonometric functions.
Printed along the top edge of the slide rule are three scales. The top scale, labeled for "POLV:" and "LIB: S:", has values descending from 10 to 1. The center scale, for "SAG:V:D:B:", has values descending from 120 to 1. The bottom scale, for "FERRO: L: G:", has values descending from 100 to 1.
Several tables containing numerical data and instructions for setting the slide are printed along the rule's bottom edge.
Part of the left end of the face of the bottom slide has been broken off.