684 Molesworth’s pocket-book
Slide Rule.
The common slide rule consists of 4 scales; A and I) fixed,
and 15 and C sliding. All are spaced us the logarithms of tho
numbers they rep: esent, so that by sliding one scale against
another, logarithmic fuuetiohs are mechanically performed.
A, B, and C are identical in their divisions, whil-t the divi-
sions of D are twice tho size of thp.-e on the other scales, or
spaced as the logarithms of the square roots of the other scales.
Examples of Working the Slide Rule.
In the following examples the letters A, B, C, D denote
the respective scales on which the reading Is to be found;
I’ denotes the gauge point (see below); d = diameter, or side
of square ; I = length ; iv — weicht, or cubic contents ;
C\ and Co denote the first and second half of C scale respec-
tively. hi questions involving the squire root: if the num-
ber of digits be o id, the working must be on Aj or Cj ; but if
the number of digits he even, it must be on A.L> or C2, as the
case may be. In questions not involving any root or power
it is immaterial whether the working is on the first or second
half qf the scale.
• Case. 1st Term. 2nd Term. 3rd Term. 4th Term.
Set ON AND AGAINST IS Answer.
1 2 3 4 5 6 7 8 9 10 11 12 Multiplication .. .. Division Proportion Inverse Proportion > (Invert Slide) 5 CircleCircumferenoe( (P = 3’14) .. < Circle Area (P=-785) Strength, Weight, > or Contents .. f Mensuration of Solids Contents of Sphere j or Cube .. .. J Squaring Square Root (digits ( odd) J Ditto (digits even) .. Side' of Square or » Rectangle .. j Cube .. 12 X 23 54 ~ 24 7:51:;31 1:54::x : 239 for d — 15 ford = 6-35 d-2 + 1' Id-i-i-P di 4-P (5-5? a/6‘5 nJ 65 1 B 21 A 7 15 *0 1 B 1 A PA PA PA 1 J) 1 C 1C 23 A 1 15 54 A 230 A 3-14 A •785 B 1-B ZB <ZB 1C ID 1 D 12 B 51 A 31 B 54 0 15 B 6-35 D <ZD di) dD 5-51) 6-5Cj 65 C2 276 A 2-25 B 239 A 31 A 41-1 A 31-7 C w C wC røC 30-25 C2 2-55 D 8-06 D
14 ^25 X V6 (7-3)3 16 C ion 76 D 7-3C 25 C 7-3 D 43-6 D 389 C