y.
Funnels of steam boats. _See_ Chimneys.
Furnaces, proper mode of firing,
smoke burning: Williams's argand;
Prideaux's;
Boulton and Watt's dead plate;
revolving crate;
Juckes's;
Maudslay's;
Hull's, Coupland's, Godson's, Robinson's, Stevens's, Hazeldine's,
&c..
Furnaces of marine boilers, proper length of.
Furnace bridges, benefits of.
Fusible metal plugs useless as antidotes to explosions.

Gauges, vacuum,
steam;
gauge cocks and glass tubes for showing level of water in boiler,
description of.
Gauge cocks for showing level of water in boiler.
Gearing for screw engines.
Gibs and cutters, strengths proper for.
Giffard's injector.
Glass tubes for showing water level in boilers.
Glass tube cocks.
Gonzeubach, expansion valve by.
Gooch's indicator.
Gooch's locomotive.
Governor or conical pendulum,
description of.
Governor, Porter's patent.
Gravity, centre of.
"Great Western," boilers of, by Messrs. Maudslay.
Gridiron valve.
Griffith's screw.
Grinding corn, power necessary for.
Grinding of cylinders.
Gudgeons, strength proper for.
Guides of locomotives.
Guides of direct acting screw engine.
Gun metal, strength of.
Gyration, centre of.

Harvey and West's pump valves.
Hawthorn, expansion valve by.
Heat, latent, definition of.
Heat, specific, definition of.
Heat, Regnault's experiments on.
Heat, loss of, by blowing off marine boilers.
Heating surface of boilers.
Heating surface per square foot of fire bars in locomotives,
a cubic foot of water evaporates by five square feet of heating surface.
Heating of bearings, causes of,
bearings should always be slack at the sides, else the pressure is
infinite.
High pressure engine, definition of.
High pressure engines, power of.
High speed engines,
arrangements proper for high speeds.
Hoadley's portable engine.
Hodgson's screw.
Hoe & Co.'s steam engine.
Holding down bolts of marine engines,
or bolts for securing engines to hull.
Holms's screw propeller.
Horses power, definition of,
nominal horse power;
actual power ascertained by the indictator;
Admiralty rule for.
Hot water or feed pump, description of.
Hot well, description of.

Increasing pitch of screw.
Incrustation in boilers. _See_ also Salt.
India rubber valves for air pump.
Indicator, description of the,
by McNaught, structure and mode of using;
Gooch's continuous indicator.
Injection cock.
Injection cocks of marine engines at ship's s