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COPYRIGHT, 1895,
BY EDWARD A. BOWSER,

1 Ei

Gen. ait. 71-1924

EXPLANATION OF THE TABLES.

PRELIMINARY NOTIONS.

1. The numerical calculations which occur in Trigonometry are very much abbreviated by the aid of logarithms. The rules for their use are as follows:

The logarithm of a product is equal to the sum of the logarithms of its factors.

The logarithm of a quotient is equal to the logarithm of the dividend minus the logarithm of the divisor.

The logarithm of any power of a number is equal to the logarithm of the number multiplied by the exponent of the power.

The logarithm of any root of a number is equal to the logarithm of the number divided by the index of the root.

For the investigations of these rules the student is referred to the “ Treatise on Trigonometry,” p. 87, or to works on Algebra.

The Common Logarithms (Briggs's) are the only ones used in extensive numerical calculations, and the only ones given in the following tables.

The common logarithm of a number is. the exponent of that power of 10 which is equal to the number.

Thus, the logarithm of 100 is 2, because 10% = 100. This is usually written log 100 = 2. 10 is the base of the common system.

2. A system of common logarithms means the logarithms of all positive numbers to the base 10.

From the above definition of common logarithms, it follows that 10° = 1, .. log 1 - 0); 10-1=.1,

.. log 0.1 101 = 10, :: log 10

.. log 0.01 102 = .. log 100 2 ; 10-3 = .001, .. log 0.001

-3, 103 = 1000, .. log *000 = 3; etc.

log 0.0001 = -4, etc.

2-1, -2,

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1; 10-2

.01,

100,

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