Water in aquariums, to aërate, [22].

Water-turtles, a trap for, [171], [172].

Water-wheels: different kinds, [201];

the modern turbine, [202];

a simple paddle-wheel, [202], [203];

a wagon wheel, [203], [204];

a barrel-wheel, [204], [205];

an undershot-wheel, [206];

a power-wheel, [206], [207], [208].

Weasel, curing the skin of, [347].