I. Solution of water in air; in the matter of heat; pulse-glass. 2. Heat is the principal cause of evaporation; thermometer cooled by evaporation of ether; heat given from steam to the worm-tub; warmth accompanying rain. 3. Steam condensed on the eduction of heat; moisture on cold walls; south-west and north-east winds. 4. Solution of salt and of blue vitriol in the matter of heat. II. Other vapours may precipitate steam and form rain. 1. Cold the principal cause of devaporation; hence the steam dissolved in heat is precipitated, but that dissolved in air remains even in frosts; south-west wind. 2. North-east winds mixing with south-west winds produce rain; because the cold particles of air of the north-east acquire some of the matter of heat from the south-west winds. 3. Devaporation from mechanical expansion of air, as in the receiver of an air-pump; summer-clouds appear and vanish; when the barometers sink without change of wind the weather becomes colder. 4. Solution of water in electric fluid dubious. 5. Barometer sinks from the lessened gravity of the air, and from the rain having less pressure as it falls; a mixture of a solution of water in calorique with an aerial solution of water is lighter than dry air; breath of animals in cold weather why condensed into visible vapour and dissolved again. NOTE XXVI ... SPRINGS. Lowest strata of the earth appear on the highest hills; springs from dews sliding between them; mountains are colder than plains; 1. from their being insulated in the air; 2. from their enlarged surface; 3. from the rarety of the air it becomes a better conductor of heat; 4. by the air on mountains being mechanically rarefied as it ascends; 5. gravitation of the matter of heat; 6. the dashing of clouds against hills; of fogs against trees; springs stronger in hot days with cold nights; streams from subterranean caverns; from beneath the snow on the Alps. NOTE XXVII ... SHELL-FISH. The armour of the Echinus moveable; holds itself in storms to stones by 1200 or 2000 strings: Nautilus rows and sails; renders its shell buoyant: Pinna and Cancer; Byssus of the antients was the beard of the Pinna; as fine as the silk is spun by the silk-worm; gloves made of it; the beard of muscles produces sickness; Indian weed; tendons of rats tails. NOTE XXVIII ... STURGEON. Sturgeon's mouth like a purse; without teeth; tendrils like worms hang before his lips, which entice small fish and sea-insects mistaking them for worms; his skin used for covering carriages; isinglass made from it; cavear from the spawn. NOTE XXIX ... OIL ON WATER. Oil and water do not touch; a second drop of oil will not diffuse itself on the preceeding one; hence it stills the waves; divers for pearl carry oil in their mouths; oil on water produces prismatic colours; oiled cork circulates on water; a phial of oil and water made to oscillate.