To find the resistance per mile, in ohms, of copper wire of high
conductivity, at 60° F. the diameter being given in mils. (1 mil. =
0·001 in.).
Set diameter of wire in mils. on C to 54,900 on A, and over R.H. or L.H.
index of B read resistance in ohms on A.
EX.—Find the resistance per mile of a copper wire 64 mils. in
diameter.
Set 64 on C to 54,900 on A, and over R.H. index of B read 13·4 ohms
on A.
To find the weight of copper wire in lb. per mile.
Set 7·91 on C to diameter of wire in mils. on D, and over index of B
read weight per mile on A.
Given electromotive force and current, to find electrical horse-power.
Set 746 on C to electromotive force in volts on D, and under current in
ampères on C read electrical horse-power on D.
Given the resistance of a circuit in ohms and current in ampères, to
find the energy absorbed in horse-power.
Set 746 on B to current on D, and over resistance on B read energy
absorbed in H.P. on A.
EX.—Find the H.P. expended in sending a current of 15 ampères through
a circuit of 220 ohms resistance.
Set 746 on B to 15 on D, and over 220 on B read 66·3 H.P. on A.