Slide rule#Circular slide rules

The slide rule is a tool for adding, subtracting, multiplying, dividing and other arithmetic operations. It corresponds to the slide rule essentially.

Pros and cons of the slide rule over the slide rule

In essence, the advantages and disadvantages are the same as the slide rule. As another are:

An advantage is the fact that a " strike-through " ( by pushing) is the " tongue " ( portable scale of the slide rule ) constructively neither possible nor necessary; Scale end and beginning of the scale of the moving part are the same place.

Transfers can be treated very easily.

In the setting of conditions (eg the three- set) to create a continuous table of values ​​is possible. This property made ​​the slide rule especially popular in graphic design and is still appreciated by many.

The accuracy and resolution of the scale is directly related to the length of the scales. By the attachment of the scale on a circular disk, the computing device is very compact. Calculating the diameter of a disk is about 1 /3 of the length of the slide rule.

The disadvantage is that on a slide rule, only a limited number of special scales may be appropriate, as space is limited on the one hand and on the other hand so that their resolution / accuracy decreases the length of the scale and to the center of the disc. For this reason, differently scaled discs were quite prepared for special applications (commercial computing and calculating, percentage, arithmetic navigation in sea and air travel, etc.). In aviation, see special rules, disc calculators to use today that are used to calculate parameters such as flight time, speed or fuel consumption. This hold is probably due to the possibility for one-handed operation and independence of batteries and the readability of different variants of a solution.

Watches

There are still watches (especially so-called pilot watches ), equipped with a circular slide rule, about Breitling, Citizen, Revue Thommen, sense or TAG_Heuer. In addition to general arithmetic operations, this can also Geschwindigkeitsberechungen or - be designed for ballistic calculations - in the military field.

Photography

Especially in analog photography, disc calculators for determining the exposure parameters (exposure time, f-number) or depth-of- range is used. Even with the manual processing of films and in the manual exposure and development of prints, disc calculators are used to determine the development and exposure times.

Trivia

A slide rule is often found on the back of a parking disc, even if it is not working exactly. With her ​​example, may be calculated fuel consumption.