A tiny working model of a triple expansion engine, made by Robert Bunge of New York, is perhaps the finest piece of skilled work of its kind that has ever been brought to the attention of ourcontemporary, the the " Scientific American." The engine measures 3 1/2 in. across the bedplate, and stands 3 1/4 in. from the bottom of the bedplate to the top of the cylinder covers. Every part is perfect. It is even equipped with the link reversing motion. With a steam pressure of 100 lb., 7200 revolutions per minute are made, turning a screw 2 1/2 in. in diameter by 7 in. pitch. The high-pressure cylinder is 5-16 in. in diameter, the intermediate cylinder 8-16 in., and the low-pressure cylinder 10-16 in. The valves are of the regular piston type for cylinders, and measure 5-32 in., 7-32 in. and 9-32 in. in diameter. The shaft, the crank and the crank-pins are all turned from one piece of steel, which in itself is rather a neat piece of work. The eccentrics are split and are exact miniature duplicates of those used on engines actually in service. The nuts used in the construction of the model are for the most part a fraction less than 1-16 in. in diameter, and yet each is perfectly hexagonal. The studs are a little less than 1-32 inch in diameter and are threaded at both ends, one end screwing into the machine and the other receiving the nuts. The crossheads are made of steel, and are fitted with brass shoes that can be taken off whenever wear occurs. The steam pipe is 1/8 in. in diameter, and the exhaust is 3-16 in. in diameter. The maker may well claim for this model that it is the smallest triple-expansion engine in the world.