Collectible Slide Rules

Collectible Slide Rules

Nostalgic original Keuffel and Esser slide rules with their advanced trigonometric and logarithmic scales invoke fond memories in accountants, engineers, scientists, and business consultants. Undergraduate and graduate college students majoring in math, science, or engineering who graduated prior to 1976 used this mechanical analog computer in their multiplication and division of extremely large and infinitesimally small numbers. Slide rules, also called slip sticks, consisted of two stationary rules and an interlocked central sliding rule with scaled numbers and a clear plastic cursor with a vertical line to slide to corresponding numbers on multiple scales.

During 1867, William J. D. Keuffel and Herman Esser (K & E) incorporated the first company to manufacture and offer drafting, surveying, and mechanical calculators for sale in the United States. Erudite scientists, executives, professors, and college students relied on K & E accuracy, durability, and bearing slide for smooth effortless calculations. K & E symbolized quality and integrity.

Breitling, a Swiss watch company, released their pilot's slide rule and their pilot's wristwatch in 1952. Specifically adapted for flight calculations, the Breitling Navitimer model calculated airspeed, rate of elevation or descent, flight time, distance, and fuel consumption for pilots. Their "navigation computer" also converted distance in kilometers to nautical miles and fuel consumption from gallons to liters.

Aviation safety is the most compelling use of slide rules in 2017. E6B circular calculators are an internationally required manual backup for aircraft avionics systems which can fail during an emergency.

Simple circular slide rules, used by graphic artists, are proportion wheels used to determine the scale factor necessary to enlarge or reduce an image to fit it into a background or within an illustration.

You'll choose from durable wooden or bamboo with engraved scales in original leather cases or cheaper plastic rules with painted scales, but paint may wear off with use.

• Simplex Linear: Simplex models use two scales of base ten logarithms on its front and slide to perform multiplication and division in scientific notation. A sliding line over the scales on each of the three rules displays your answer.
• Duplex linear: Duplex models have scales of logarithms on their front, back, and slide, which can be removed, turned, and reinserted for additional calculations.
• Circular Models: Circular models with spiral scales of logarithms are the most accurate. The base of the circular rule is suspended above a central pivot. A circular rule has one or two cursors.
• E6B Circular: Pilots are required to be proficient on the E6B slide rule. The E6B circular rule scales are used internationally for safe manual calculation of air time, distance, speed, temperature, compass errors, and fuel consumption.