# Slide rules and other mathematical instruments

 The saying that a prophet has no honour in his own country is well exemplified in the case of the Slide Rule and its invention. For many years this useful instrument was greatly undervalued in England, the country in which it was invented, and even as late as 1850 it was very little known. Yet as De Morgan has put it "for a few shillings most persons might put as much power of calculation in their pockets many hundred times as contained in their heads and the use of this instrument is attainable without any knowledge of the properties of logarithms on which principle it depends. R. T. Gunther, Historic Instruments for the Advancement of Science Oxford, (1925)

### Slide Rules

 The invention of the slide rule. There was, at the time, considerable controversy about who invented the slide rule. Strong words were traded between the protagonists in the introductions of various books. Oughtred's Circle of proportion. William Oughtred (1574-1660) wrote a number of important mathematical works including Clavis Mathematicae (Key to Mathematics), London (1631) and ``The Circles of Proportion and the Horizontal Instrument" London (1632). Isaac Newton's slide rule. Isaac Newton used slide rules to solve polynomial equations. Non-logarithmic slide rules. Slide rules and logarithms are synonymous. Thus, it may come as a surprise to discover that to produce a slide rule capable of multiplying two numbers is is not necessary to use logarithms. Slide rules for special purposes. Many slide rules are designed for special purposes. How is this done? Mathematics Galore! In my book, Mathematics Galore! co-authored with Prof. Chris Budd, University of Bath, Chapter 9 - Doing the sums - is an explanation of logarithms and, of course, their practical implementation in the form of the slide rule. Bibliography. This short bibliography contains a miscellany of articles on subjects of interest: slide rules, sectors, logarithms, mathematics, history of science etc. Slide rule scales. Lists of some of the more common scales that appear on slide rules can be found here.

There are some goodies for you to download. This includes a selection of cut-out and keep slide rules I've designed, some articles and other information.

### Logarithms

John Napier invented the logarithm and published his Cannon in 1614. Have a look at a page from his original tables or read his introduction ([PS]). Interestingly John Napier invented many other aids to calculation. Perhaps the most famous of these are his bones. When laid out in the correct manner they can be used as a set of multiplication tables.

### Sectors

A sector is a mathematical instrument consisting of two hinged arms with various scales. Tell me more.

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### Other items of interest

The following are either items I'm hosting or external links.

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[Slide rule page] [Chris Sangwin]