# The Slide Rule Essay Research Paper The — страница 2

desk or at an antique shop. The basic slide rule instructions start out with multiplying numbers on the slide rule. To multiply two numbers on the typical slide rule, the user sets the left index (start of the scale) on the C scale to line up with one factor on the D scale. The user then finds the second factor on the C scale and looks on the D for the product. By doing this, the user effectively added the logs (lengths) of the two numbers and look up the antilog. Multiplication with more than a single digit were carried out by making use of the smaller graduations to represent additional digits of decreasing significance. The accuracy the slide rule gave depended on the size of it. Also, the slide rule did not indicate the decimal point and the user usually had to estimate. For example: Here the answer is 7, which is changed to the hundreds to equal 700. If you multiply 42.2 and 16.6 you will find that the answer is 700.52. Division was performed by reversing the multiplication steps (setting the divisor on the C scale opposite the dividend on the D scale and reading the result of the D scale under the C scale index). To multiply multiple numbers, the user simply moved the C index to the previous product to start the next multiplication. Slide rules have drawn on them a variety of scales, depending on what one you have or need. These scales originally went by a variety of names, but since the introduction of the Mannheim they have been standardized as follows: C,D- These are the basic multiplication scales. A,B- These scales are also used as multiplication scales. More importantly they are the squares of C and D scales. CF,DF- These are also called the folded scales. They are constructed the same as the C and D scales, but start and at pie (3.14). CI, DI, CIF, DIF- These are the inverse scales. They are exactly the same as the C and D scales, but arranged right to left. Numbers appearing on these scales are the reciprocals of the basis scale. S, T, ST- These are the basic trigonometry scales. K- This scale is used for finding cubes and cube roots. L- This scale is used to find common logarithms directly. LL0, LL1, LL2, LL3- These are called the LL scales and are used to obtain powers and roots of numbers from 1.001 to 22,000. Ln- This scale is used to find the natural logarithm directly. Sh, Th- These scales are for the sine and tangent functions. P- This is the Pythagorean scale, used in finding the base of a right triangle if the hypotenuse and heights are known. This picture shows a full scaled or complicated slide rule. Even though slide rules are obsolete today, they are still around. Many collectors today trade, buy, and sell slide rules. These collectors developed their own ?slide rule society?, called The Oughtred Society. The Oughtred Society was formed in 1993 to serve the needs of the growing number of slide rule collectors. Starting out with only 11 charter members in June of 1991, the society has grown to become a worldwide organization with over 350 members. The society has established a journal, published a bi- annual swapsheet (which is like the classified ads of slide rule collectors), and sponsored a series of popular annual meetings and conventions of collectors. The society has become a valued network for contact and exchange between slide rule collectors. The slide rule was once a great invention that lasted for over three hundred years. They were used by some of the earliest of mathematicians to help develop theories or ideas that they are now famous for. Now, hand-held calculators are used everywhere from the classroom to a construction site. They were a crucial part of the development of modern math and have helped in the world advance in technology.

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