(14) W.G. says, in reply to C.W.W., who has an engine, of 2-5/8 inches bore and 4 inches stroke, which runs slower with increase of pressure: Having had much experience with small engines and boilers, I will state that I have had the same difficulty when using an upright tubular boiler, and discovered the following to be the cause: The upper portions of the tube superheat the steam to such a degree as to prevent lubrication on the valve and piston surface by condensation, and thereby reduce the speed of engine. Even with increased pressure, this effect will be more appreciable when the area and travel of slide valve are in excess.
(15) J.M.T. asks: Is there friction between two bodies while at rest, or only when one or both are in motion? A. Both when at rest and in motion.
Why does a balloon rise in the air? A. See p. 64, vol. 32.
(16) S.J.S. asks: 1. How are augers twisted? A. By special machinery. 2. How are twist drills made, and are they single or double grooved? A. They are double grooved or double twisted, and are cut out in a milling machine.
Can weights, springs, or water from a tank be used to any advantage to run a lathe? A. No.
How much do iron and brass, in rods or bands, expand in length when heated to red heat? A. Iron about 1/8 inch per foot, brass 1/10 inch.
Is the pressure of the air to be added to the weight of water in the bottom of a vessel in estimating the pressure on the bottom? A. No.
Does a watch or clock run faster when just wound up? A. No.
Is it not moisture in the air that makes it heavier, and so affects the barometer? A. Yes.
Is the pressure in a siphon equal throughout, or is it greater in the upper end? A. Equal throughout.