Palmer's Computing Scale, revised issue one
Date: 1843
Inventory Number: 1993-1-0003
Classification: Slide Rule
Dimensions:1.2 × 27.9 × 28 cm (1/2 × 11 × 11 in.)
Accessories: grey fabric cord, appears to be from Harvard Libraries envelope (see 5464)
DescriptionYellowed cardboard square, with brown, gold-embossed leather edges, joined at center by a metal fastener to a yellowed cardboard disc. A flowered pattern is engraved in each of the square's four corners. A second metal fastener is attached near the top of the top disc.
Printed on the cardboard square around the circumference of the top disc is a logarithmic scale carrying values 1 to 10. A diamond is printed to the right of the 1 mark; "B.G" is printed near the 2.8 mark; "D" is printed near the 3.1 mark; "W.G. is printed near the 3.4 mark; and an "A" is printed near the 7.9 mark. Eight points on the scale are additionally labeled with a star and the following text: near the 4.6 mark, "Days / 8 perct"; near the 5.2 mark, "Days / 7 perct"; near the 6.1 mark, "Days / 6 perct"; near the 7.3 mark, "Days / 5 perct"; near the 1.5 mark, "Months / 8 perct"; near the 1.7 mark, "Months / 7 perct"; near the 2 mark, "Months / 6 perct"; and near the 2.4 mark, "Months / 5 perct".
Printed around the circumference of the top disc is a second logarithmic scale, also carrying values 1 to 10. Six points on the scale are additionally labeled with the following: near the 1.3 mark, "Cont"; near the 1.4 mark, "S. Feet"; near the 1.6 mark, "Acre"; near the 3.1 mark, "C"; near the 7.1 mark, a circle; and near the 8.9 mark, a square.
Directions for using the slide rule are printed on the back of the cardboard square, surrounded by an engraved geometric border.
This instrument, together with 5465 and 5466, is stored in a grey cardboard envelope with fabric tie from Harvard College Libraries. A Harvard College Library bookplate is affixed to the inside front cover the envelope; a pocket for circulation cards is attached to the back inside cover.
Signedface, center of top disc: PALMER'S / COMPUTING SCALE ;
face, top disc, bottom center: Entered according to Act of Congress in year 1843 by Aaron Palmer in the Clerks Office of the District Court of the State of Massachusetts;
face, top disc, bottom center: Engraved by George G. Smith 186 Washington St. Boston
FunctionEarly circular slide rule used to solve mathematics problems, including multiplication, division, the calculation of interest, and geometry problems.
This issue was circulated following the discovery that three gauge points ("D", "B.G.", and "W.G.") were missing from the first issue, see 5464, DW0649.
Primary SourcesPalmer, Aaron. A key to the endless, self-computing scale, showing its application to the different rules of arithmetic &c. Rochester, NY: P.S. Stoddard, 1842.
ProvenanceEmeritus Professor at the Harvard University Mathematics Department, 1993.
Related WorksFeazel, Bobby. "Palmer's Computing Scale." Journal of the Oughtred Society 3, no. 1 (March 1994): 9-17,
Feazel, Bobby. "Palmer's Computing Scale -- Revisited." Journal of the Oughtred Society 4, no. 1 (March 1995): 5-8.