Editing Slide rule (section)

===Specialized calculators===
Slide rules have often been specialized to varying degrees for their field of use, such as excise, proof calculation, engineering, navigation, etc., and some slide rules are extremely specialized for very narrow applications. For example, the John Rabone & Sons 1892 catalog lists a "Measuring Tape and Cattle Gauge", a device to estimate the weight of a cow from its measurements.

There were many specialized slide rules for photographic applications. For example, the [[actinograph]] of [[Hurter and Driffield]] was a two-slide boxwood, brass, and cardboard device for estimating [[Exposure (photography)|exposure]] from time of day, time of year, and latitude.

Specialized slide rules were invented for various forms of engineering, business and banking. These often had common calculations directly expressed as special scales, for example loan calculations, optimal purchase quantities, or particular engineering equations. For example, the [[Fisher Controls]] company distributed a customized slide rule adapted to solving the equations used for selecting the proper size of industrial flow control valves.<ref>{{cite web|url=http://www.natgasedu.com/vm004.html |archive-url=https://web.archive.org/web/20100106031649/http://www.natgasedu.com/vm004.html |archive-date=6 January 2010 |title=Fisher sizing rules |access-date=2009-10-06 |work=natgasedu.com |url-status=dead }}</ref>

Pilot balloon slide rules were used by meteorologists in weather services to determine the upper wind velocities from an ascending hydrogen or helium-filled pilot balloon.<ref>{{cite web|url=http://www.pilotballoon.com/slide.htm|title=Pilot Balloon Slide Rules|work=www.pilotballoon.com|access-date=28 September 2016|archive-url=https://web.archive.org/web/20160928041013/http://www.pilotballoon.com/slide.htm|archive-date=2016-09-28|url-status=dead}}</ref>

The [[E6B|E6-B]] is a circular slide rule used by pilots and navigators.

Circular slide rules to estimate ovulation dates and fertility are known as ''wheel calculators''.<ref>{{cite journal |doi=10.1080/14767050412331312200 |pmid=15061314 |title=Circle of time: errors in the use of the pregnancy wheel |journal=Journal of Maternal-Fetal and Neonatal Medicine |date=2003 |volume=14 |issue=6 |pages=370–372 |first=M. G. |last=Ross }}</ref>

A Department of Defense publication from 1962<ref>{{cite web|url=https://www.fourmilab.ch/etexts/www/effects/|title=The Effects of Nuclear Weapons|access-date=2021-05-02}}</ref> infamously included a special-purpose circular slide rule for calculating blast effects, overpressure, and radiation exposure from a given yield of an atomic bomb.<ref>{{cite web|url=https://www.fourmilab.ch/bombcalc/|title=Strangelove Slide Rule|access-date=2021-05-02}}</ref>

<gallery>
File:E6b-front.jpg|An E6-B aviation computer
File:John Rabone 1892 Cattle Gauge.png|John Rabone & Sons 1892 cattle gauge
File:HD Actinograph.jpg|[[Hurter and Driffield]]'s [[actinograph]]
File:Cryptographic sliding rule-IMG 0533.jpg|Cryptographic slide rule used by the Swiss Army between 1914 and 1940
Keuffel & Esser Model 4180, Fraction Adder - MIT Slide Rule Collection - DSC03616.JPG|Rare fractional adder
</gallery>