[7] Karl von Gebler (Galileo), p. 13.
[8] It is of course the "silver lining" of clouds that outside observers see.
[9] L.U.K., Life of Galileo, p. 26.
[10] Note added September, 1892. News from the Lick Observatory makes a very small fifth satellite not improbable.
[11] They remained there till this century. In 1835 they were quietly dropped.
[12] It was invented by van Helmont, a Belgian chemist, who died in 1644. He suggested two names gas and blas, and the first has survived. Blas was, I suppose, from blasen, to blow, and gas seems to be an attempt to get at the Sanskrit root underlying all such words as geist.
[13] Such as this, among many others:—The duration of a flame under different conditions is well worth determining. A spoonful of warm spirits of wine burnt 116 pulsations. The same spoonful of spirits of wine with addition of one-sixth saltpetre burnt 94 pulsations. With one-sixth common salt, 83; with one-sixth gunpowder, 110; a piece of wax in the middle of the spirit, 87; a piece of Kieselstein, 94; one-sixth water, 86; and with equal parts water, only 4 pulse-beats. This, says Liebig, is given as an example of a "licht-bringende Versuch."
[14] Draper, History of Civilization in Europe, vol. ii. p. 259.
[15] Professor Knight's series of Philosophical Classics.
[16] To explain why the entire system, horse and cart together, move forward, the forces acting on the ground must be attended to.