C-Thru pocket slide rule
Date: circa 1960
Inventory Number: 2003-1-0211
Classification: Slide Rule
Dimensions:0.1 × 16.3 × 3 cm (1/16 × 6 7/16 × 1 3/16 in.)
DescriptionMoveable white plastic slide inside white plastic sleeve, with clear plastic runner. Rule is printed in black and red; runner is printed with a black hairline on both sides.
The face of the sleeve is printed with two scales. Scale "A," above the slide, carries values from 1 to 10. Scale "D," printed below the slide, also has values ranging from 1 to 10.
The top edge of the face of the slide is printed with an inch rule (6 inches). The bottom edge of the slide is printed with a centimeter rule (15.3 centimeters). Neither rule is visible when the slide rule is in the sleeve.
Inside the two rules, the face of the slide is printed with three additional scales. The top and bottom scales, "B" and "C," respectively, carry values from 1 to 10. The center scale, C_1, has values descending from 10 to 1.
The back of the sleeve is printed with a table of decimal equivalents. The back of the envelope is printed with three scales. The top scale, "S," carries values from 40' to 75°. The center scale, "L," has values ranging from 0 to 10. The bottom scale, "T," carries values from 6 to 45.
The inside of the sleeve is printed with a list of unit equivalents.
Signedunsigned
FunctionFor use in solving multiplication, division, and trigonometric problems, and in finding squares, square roots, and cubes.
To read numbers higher than ten, the user locates the first digit of the number on the prime line of the relevant scale, the second digit on the secondary line to the right thereof, and so on. The final digit determines the position of the value on the scale.
To multiply, the user first moves the slide to left or right such that the 1 on the C scale coincides with the value of the multiplicand on the D scale. Then, holding the slide in place, he moves the runner to left or right until the hairline is over the value of the multiplier on the C scale. The coincident value on the D scale is the product.
To divide, the user first moves the slide to left or right such that the value of the divisor on the C scale coincides with the value of the divident on the D scale. Then, holding the slide in place, he locates the 1 on the C scale. The coincident value on the D scale is the quotient.
To square a number, the user moves the runner to left or right until the hairline is over the appropriate value on the D scale. The value under the hairline on the A scale is the first number's square.
To take the square root of a number, the user moves the runner to left or right until the hairline is over the appropriate value on the A scale. The value under the hairline on the D scale is the first number's square root.
To take the logarithm of a number, the user first moves the runner to left or right until the hairline is over the appropriate value on the D scale. then, holding the runner in place, he turns the slide rule over. The value under the hairline on the L scale indicates the logarithm of the first number.
To find the cube of a number, the user first moves the slide to left or right such that the 1 on the C scale coincides with the value of the number to be cubed on the D scale. Then, holding the slide in place, he locates this same value on the B scale. The coincident value on the A scale is the first number cubed.
Primary SourcesAdditional images of this model can be found here.
Its instruction card is here.