There is a little trick in the mounting of prints that is well worth adopting. That is to say, it may be of advantage to those who mount their prints when dry. In my immediate household there are three aspiring amateurs, and among the lot there is owned about everything that is intended to make the following of photography easy. Long ago - five or six years, to be precise, one member bought a print roller, and for a time we could none of us do anything without it. But those days are gone and the roller is packed away somewhere with a lot of other outlawed truck, lanterns, etc., now voted of no earthly use. One of us happens to be in a place that does mounting and printing for professionals, and was surprised to see with what ease and celerity the prints were fixed on the cards. The operator despised the use of a roller and did the work excellently well with - what do you suppose?-a silver half dollar.
With this or a similar coin the print can be quickly rubbed into contact in every part much better, in my humble opinion, than is possible with the most expensive print roller. The abraded edges of the coin insures that every portion should be rendered in contact and all superfluous paste pushed outward to the edges. A smaller coin will answer in a pinch ; in my own case I keep for the purpose an English penny, and one would be surprised to see how the image on it has worn down by a few years of use. For the past four years not one of us has used the roller and find that the coin serves every need in mounting.. I have never seen this idea exploited, and assure the reader that it is something that will pay to investigate.
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 yet been brought to the attention of our contemporary, the "Scientific American" The engine measures 3 1/2 in. across the bedplate, and stands 3 1/2 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 pounds, 7260 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 all cylinders, and measure 5-32, 7-32 and 9-32 in. in diameter. The shaft, the crank and the crank-j)ins 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. The studs are a little less than 1-32 in. 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 - expausion engine in the world.