a captive body, a moving body is propelled against more or less stationary air. The resolution of forces is shown by the arrows as before.
Up to the present time no practical flying-machine has appeared. But experimenters are hard at work examining the conditions which must be fulfilled to enable man to claim the "dominion of the air."
Chapter XVIII.
HYDRAULIC MACHINERY.
The siphon—The bucket pump—The force-pump—The most marvellous pump—The blood channels—The course of the blood—The hydraulic press—Household water-supply fittings—The ball-cock—The water-meter—Water-supply systems—The household filter—Gas traps—Water engines—The cream separator—The "hydro."
In the last chapter we saw that the pressure of the