What Is a Slide Rule?

A slide rule , or slide rule , is a logarithmic slide rule . It is an analog computer. It usually consists of three locked bars and a sliding window (called a cursor). Used extensively before the 1970s, it was replaced by electronic calculators and became obsolete.

In its most basic form, slide rules use two logarithmic scales for multiplication and division. These are common operations that are time-consuming and error-prone on paper. The user decides by estimation

Traditionally, slide rules are made of hardwood, such as mahogany or boxwood, plus glass or metal chute. In 1895, a company started making slide rules from bamboo, which had the advantage of being less sensitive to temperature and humidity. These bamboo slide rules were introduced in the autumn of 1933

The slide rule was invented around 1620--1630, at John Napier

Pros: Slide rule tends to correct "false precision" and significant digit errors. The accuracy of slide rule users is usually 3 digits. This is consistent with the data used in most engineering formulas (for example, material strength, accurate to 2 to 3 digits of accuracy, and a large number of safety factors-typically 1.5 times or more-exist, as building-level errors, changes, and materials Additional corrections). When using a modern pocket calculator, the accuracy is displayed as 7 to 10 digits, and in reality, the result cannot be more accurate than the input number.

Slide rules need to be estimated on the order of magnitude. On a slide rule, 1.5 30 (equal to 45) and 1,500,000 0.03 (equal to 45,000) have the same result. It depends on the "effectiveness" of the engineer's continuous estimation results: this often does not exist in the use of computer programs or calculators, for example, it may be an employee who does not have the ability to judge the reasonableness of the numbers while operating the calculator.

When calculating a series of multiplications or

Emperor Kangxi first used slide rule in Chinese history. He used an ivory Gantt style slide rule.

Before the 1970s, Chinese science and engineering students had a hand in hand and were indispensable computing tools. The natural pair slide rule manufactured by Shanghai slide rule factory is modeled after Keuffel & Esser, and another type of short slide rule is modeled after Faber-Castell of Germany, which is precise and beautiful.

KE slide rule without centimeter and millimeter scale; German Faber-Castell slide rule has the advantages of centimeter,

For the reasons given above, some people still prefer to use a slide rule rather than an electronic calculator as a practical calculation tool. Many others keep their old slide rules out of nostalgia, or collect slide rules as a hobby, or as a special decoration.

Popular models include Deci-Lon by Keuffel & Esser, an advanced scientific and engineering slide rule, which is divided into 10-inch "general" type (Deci-Lon 10) and 5-inch "pocket" type (Deci-Lon 5). Another popular American model is an 8-inch scientific instrument circular slide rule. Among European models, Faber-Castell's high-end models are most popular among collectors.

Although a large number of slide rules are on the market, well-preserved specimens are often surprisingly expensive. Many slide rules sold on online auction sites have broken or missing parts. Replacement parts are scarce and therefore expensive, often only sporadic on individual collectors' websites. Keuffel & Esser models before 1950 are particularly problematic because the end of the cursor is damaged by chemical reactions over time. In many cases, the most economical way to obtain a usable slide rule is to buy more slide rules of the same model, and then assemble their parts.

The best place to look for slide rules is the "flea market". You can often buy a well-preserved KE or Faber-Castell slide rule for $ 2.