| CS378, History Of Computing Week 3, Weekly Report Due 2004 Sept 8 Reports for History of Computing CS378
The slide rule is based on the idea of using devices to solve logarithms. In order to understand why the slide rule was created, I will give a brief history of the logarithm and how people first tried making it easier to use. The idea of the logarithm is linked back to Niepers research in the 1600’s (2). His findings were presented in a document called the Mirifici logarithmorum Canonis Descriptio (1). The first known logarithmic rule was created by a fellow named Edumnd Gunter. Gunter originally began by creating tables to use for calculation at sea; he then created a “line of numbers” that could multiply two values. Around the same time William Oughtred, “a highly recognized mathematician”(1), designed a modification to Gunter’s line of numbers by adding a second ruler that could line up a second set of numbers along the first doing away with the dividers the “line of numbers” required. He also devised a circular device that would have the same effect when two different sized circles where used with markings on each one where lined up (1). After the initial invention of the slide ruler it wasn’t fully brought into use until the 19th century. (1) However it should be noted that some sources claim that the slide ruler took off during the 1700’s (2). EB also stated that in 1814 Peter Roget invented the “log-log” slide ruler for calculating powers and roots (2). I note this because the CBC did not emphasize this occurrence, which I feel was a huge step in making the slide ruler into what made it so useful as a calculating device. Mannheim from France; brought about the next modification when he added a double sided cursor to the slide rule. This had been done previously, but did not catch on. “The cursor enabled fairly complex operations to be easily carried out on a simple, yet well-made, slide rule.” (1, 31-32) This modification made the slide rule into what we know it as today.
The slide rule went on to be a staple in mathematics until the early
1960’s when calculators replaced them as the tool for logarithmic
calculations. “The scale started at one because the log of one is zero. Two numbers could be multiplied by measuring the distance from the beginning of the scale to one factor with a pair of dividers, then moving them to start at the other factor and reading the number at the combined distance(3).” The slide rule has evolved over time and became more useful with each
modification. Overall I found the three sources I used to be consistent.
They all seemed to tell the history in their own way, mainly owning up
to its audience. The CBC offered the most in-depth history, however like
stated in the Week 3 Assignment, it does not document its sources. The
encyclopedia was a surprisingly good source; it provided a reasonable
amount of history and explanation of the device. The HP Museum offered
a good technical backing of the slide ruler and its origins; however
I feel it lacked an in-depth history of the slide rule in terms of the
people who invented it. Notes 1. William Aspray, ed., Computing Before Computers (Ames, IA: Iowa State University Press, 1990 ). Also available online at http://www.computerhistory.org/collections/DocumentArchive/Documents/Books/Computing Before Computers/CBC.html (Computer History Museum, accessed 2004 Sept 7).
3. “Slide Rules.” The Museum of HP Calculators. http://www.hpmuseum.org/sliderul.htm (The Museum of HP Calculators, accessed 2004 Sept 7) A web page.
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