138

Friction and power, 55. dependent on, 59.

Guibal, M., fan in United States,

and velocity, 61.

117. chimney, 116.

Furnace, principle of, 24.

Gunpowder, charge of, 96.

position of, 24.

use of, 96.

power of, 27.

Hall's lamp, 36.

economy of, 92, 118. danger of, 109.

report, 94.

Hand fans, 69.

Galileo, 2.

Head of air, 25.

39.

Heart, action of, 9.

Gases, specific gravity of, 4. nitrogen, 5.

Heat of shafts, 24.

oxygen, 7.

Hedley, Mr., 129. Horse-power, 52.

oxide, 12.

effective, 103. nominal, 103.

carbonic acid, 9.

Hot air, 23.
Howe, R., 113.
Hutchinson, Mr., 128.
Hydrosulphuric-acid gas, 14.
Improvements in safety-lamps, 34.
Illuminating power of, 36.
Improvements in ventilation, 73.
in fans, 110.

Indicated horse-power, 101.
Indicator-cards, 103.

fan experiments, 113. fan, 115.

Nitrogen compounds, 6.
Nixon ventilator, 110.

Nominal horse-power, 103.
North of England Institute, 38, 116.
Oxygen, 7.

necessity of, S.

consumption of, 9.

starvation, 11.

Orifice of discharge, 54.
Parish safety-lamp, 36.
Peclet, 53.

Pennsylvania mine laws, 129.
Perimeter, 42.

Permanent stoppings, 74.
Phillips, Professor, 129.
Pneumatic paradox, 26.
Poisonous gases, 10, 12, 13.
Position of downcast, 24.
of fan, 28.

of upcast, 28.
of furnace, 24, 28.

Power of winds, 29.

increase of, 56.
ventilating, 55.
Pressure of air, 2, 85.

and water-gauge, 46.
total, 50.

per square foot, 50.
ventilating, 54.
defined, 55.
and length, 57.
and perimeter, 57.

and area, 58.

and friction, 59.

economy of, SS.