The water jacket is brazed to the cylinder-casting autogenously, the metal being a composition of nickel and copper known as "Monel" metal, which is proof against corrosion. Cylinders are bored, ground and finished by lapping, to get a glass smooth surface. Water Circulation: The water circulation is so carried out that all cylinders are cooled equally, the water pump being divided by a partition which passes water in equal quantities to each set of four, thus avoiding any possibility of a steam-trap on one side causing all the water to pass through the other side. The pump is driven from the crankshaft by a floating joint. The pump shaft is made of a carbon spindle steel. A portion of the hot water is returned through the carburetor water jacket, which is essential with present day gasoline, particularly in cold weather or high altitudes. Lubrication: The lubrication is a combined circulating and splash oiling system. A gear driven oil pump submerged in the oil pan forces a constant stream of filtered oil through the hollow cam shaft bearing, thence to each individual cam shaft bearing, thence to the main crankshaft bearings whence it is forced through the hollow crankshaft and cheeks to the crank pins, the surplus replenishing the oil pan into which the rods dip, thus oiling the cylinder walls by splash and also filling oil pockets on each main bearing, as an additional insurance against their running dry. The pump is driven off a bevel gear integral with the crankshaft and is of the gear type, being without valves or moving parts other than two simple spur gears. It is entirely enclosed in a fine mesh screen through which the oil must pass to reach the pump. Valves: The valves have cast-iron heads reinforced with a perforated steel disc embedded in the cast iron, the whole being electrically welded to a carbon steel stem. The cam shaft is hardened and ground and cams formed integral with the shaft. The cam contour is also ground, the valve timing being exactly the same in each cylinder. [Illustration: CURTISS MOTORS] (A) The first Curtiss aerial motor; used In Baldwin dirigible. (B) Motor used in both the "White Wing" and "Red Wing." (C) Motor of 1912. [Illustration: AT THE AEROPLANE FACTORY, HAMMONDSPORT] (A) Testing aeroplanes. Gravel on reversed planes tests strength; scale shows wire-strain. (B) Assembly room of factory. Castings: The majority of non-moving parts, including the crank case, are cast of special aluminum alloys. Recent laboratory tests have shown tensile strengths of as high as fifty thousand, five hundred pounds per square inch. Weight: The weight of model "A" motor alone is two hundred eighty-five pounds–three and eight-tenth pounds per horse-power. The weight of power plant including propeller, radiator, and necessary connections is three hundred forty-seven pounds.