Calculating disc rule
The calculating disc calculator is an aid for adding, subtracting, multiplying, dividing and other arithmetic operations. It essentially corresponds to the slide rule .
Advantages and disadvantages of the slide rule compared to the slide rule
Basically, the advantages and disadvantages are the same as with the slide rule . The following are to be mentioned:
An advantage is the fact that “pushing through” the “tongue” (movable scale of the slide rule) is structurally neither possible nor necessary; The end of the scale and the beginning of the scale of the moving part are in the same place.
Carry-overs can be handled very easily.
When setting ratios (e.g. with the rule of three ), it is possible to create an uninterrupted table of values. This property made the calculating rule particularly popular in the graphic arts industry and is still valued by some today.
The accuracy or resolution of the scales is directly related to the length of the scales. By attaching the scales to a circular disk, the calculator is very compact. The diameter of a slide rule is about 1/3 the length of a slide rule.
The disadvantage is that only a limited number of special scales can be attached to a calculating disc, since on the one hand the space is limited and on the other hand the length of the scales and thus their resolution / accuracy decreases towards the center of the disc. For this reason, differently scaled panes were produced for special applications (commercial arithmetic and calculation, percentage calculation , navigation calculations in aviation and seafaring, etc.). In aviation, special calculating disks are still used today, which are used to calculate variables such as flight time, speed or fuel consumption. These presumably hold due to the possibility of one-handed operation and the independence of batteries and the readability of different variants of a solution.
Breitling watch with disc rule
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Clocks
There are still wristwatches today (especially so-called pilot's watches ) that are equipped with a calculating disc rule, for example from Breitling , Citizen , Revue Thommen , Sinn or TAG Heuer . In addition to general arithmetic operations, these can also be designed for speed calculations or - in the military sector - for ballistic calculations.
photography
Above all in analog photography, calculating disks are used to determine the exposure parameters ( exposure time , f-number ) or the depth of field. In the manual development of films as well as in the manual exposure and development of prints , calculation disks are used to determine the development and exposure times.
Trivia
A calculation disc can often be found on the back of a parking disc, even if it is not precisely worked. It can be used, for example, to calculate fuel consumption.
Web links
- Calculating disc programmed in PostScript