Scofield-Thacher Engineer's slide rule
Date: patented 1901
Inventory Number: 1989-1-0001
Classification: Slide Rule
Dimensions:0.9 x 5.3 x 60.9 cm (3/8 x 2 1/16 x 24 in.)
Bibliography:Catalogue of Eugene Dietzgen Co.: Drawing Materials, Surveying instruments, Measuring Tapes
A History of the Logarithmic Slide Rule and Allied Instruments
Catalog of Eugene Dietzgen Co.
DescriptionRectangular wooden double-sided slide rule faced with off-white paper. On each side the top and bottom slides are fixed; the second slide moves to left and right.
The face of the rule is printed with four different scales. Along the left half of the bottom edge of the top, fixed slide is a scale labeled "B." This scale carries values from 1 to 10, divided into either fiftieths (1 to 5) or tenths (5 to 10). Along the right half of the bottom edge of the same slide is a scale labeled "D," for "ROOTS." It has values ranging from 1 to 3.16, divided into either hundredths (1 to 2) or fiftieths (2 to 3.16).
Along each of the left and right halves of the top and bottom edges of the second, moveable slide is printed a scale labeled "A." It carries values from 1 to 10, divided into either fiftieths (1 to 5) or tenths (5 to 10).
Printed along the left half of the top edge of the bottom, fixed slide is a scale labeled "C," for "RECIPROCALS." It has values descending from 10 to 1, divided into either tenths (10 to 5) or fiftieths (5 to 1). The "D" scale, for "ROOTS," is continued along the right half of the top edge of the same slide. It has values ranging from 3.16 to 10, divided into either fiftieths (3.16 to 5) or twentieths (5 to 10).
The back of the rule is printed with scales labeled "E" and "F." Printed along the bottom edge of the top, fixed slide is an "F" scale carrying values from 1 to 10, divided into either hundredths (1 to 2), fiftieths (2 to 5), or twentieths (5 to 10). The "E" scale printed along the top edge of the second, moveable slide likewise carries values from 1 to 10, divided into either hundredths (1 to 2), fiftieths (2 to 5), or twentieths (5 to 10).
The "E" scale printed along the left half of the bottom edge of the second, moveable slide carries values from 3.16 to 10, divided into either fiftieths (3.16 to 5) or twentieths (5 to 10). Along the right half of the same edge the "E" scale carries values from 1 to 3.16, divided into either hundredths (1 to 2) or fiftieths (2 to 3.16).
Printed along the left half of the top edge of the bottom, fixed slide is an "F" scale carrying values from 3.16 to 10, divided into either fiftieths (3.16 to 5) or twentieths (5 to 10). Along the right half of the same edge the "F" scale carries values from 1 to 3.16, divided into either hundredths (1 to 2) or fiftieths (2 to 3.16).
The top and bottom edges of the rule are each divided into twenty boxes. In the leftmost box on the bottom edge of the rule is a list of abbreviations used on the rest of the rule. The remaining 19 boxes contain instructions for solving various equations using the face of the rule.
The third box from the left on the top edge of the rule contains instructions for solving a single equation using the back of the rule. The next box to the right is printed with general instructions for the use of the "E" and "F" scales. The remaining boxes contain information on unit conversions.