Combined and sensible heat; chemical combinations attract heat, solutions reject heat; ice cools boiling water six times as much as cold water cools it; cold produced by evaporation; heat by devaporation; capacities of bodies in respect to heat, 1. Existence of the matter of heat shewn from the mechanical condensation and rarefaction of air, from the steam produced in exhausting a receiver, snow from rarefied air, cold from discharging an air-gun, heat from vibration or friction; 2. Matter of heat analogous to the electric fluid in many circumstances, explains many chemical phenomena. NOTE VIII ... MEMNON'S LYRE. Mechanical impulse of light dubious; a glass tube laid horizontally before a fire revolves; pulse-glass suspended on a centre; black leather contracts in the sunshine; Memnon's statue broken by Cambyses. NOTE IX ... LUMINOUS INSECTS. Eighteen species of glow-worm, their light owing to their respiration in transparent lungs; Acudia of Surinam gives light enough to read and draw by, use of its light to the insect; luminous sea-insects adhere to the skin of those who bathe in the ports of Languedoc, the light may arise from putrescent slime. NOTE X ... PHOSPHORUS. Discovered by Kunkel, Brandt, and Boyle; produced in respiration, and by luminous insects, decayed wood, and calcined shells; bleaching a slow combustion in which the water is decomposed; rancidity of animal fat owing to the decomposition of water on its surface; aerated marine acid does not whiten or bleach the hand. NOTE XI ... STEAM-ENGINE. Hero of Alexandria first applied steam to machinery, next a French writer in 1630, the Marquis of Worcester in 1655, Capt. Savery in 1689, Newcomen and Cawley added the piston; the improvements of Watt and Boulton; power of one of their large engines equal to two hundred horses. NOTE XII ... FROST. Expansion of water in freezing; injury done by vernal frosts; fish, eggs, seeds, resist congelation; animals do not resist the increase of heat; frosts do not meliorate the ground, nor are in general salubrious; damp air produces cold on the skin by evaporation; snow less pernicious to agriculture than heavy rains for two reasons. NOTE XIII ... ELECTRICITY. 1. _Points_ preferable to knobs for defence of buildings; why points emit the electric fluid; diffusion of oil on water; mountains are points on the earth's globe; do they produce ascending currents of air? 2. _Fairy-rings_ explained; advantage of paring and burning ground. NOTE XIV ... BUDS AND BULBS.