In Fig. 84 we illustrate a curious old microscope and case, made about the year 1780. It is on a mahogany stand, in which is a drawer containing four magnifying powers. It formerly belonged to a Mr. Charles Sherborne and is now in the Hull Museum, where, as the connecting link between the older type and the modern, there is another interesting microscope made some fifty or sixty years ago. The engineer, mechanic, and scientist find much pleasure in the curios which were associated with their professions in former days, and delight in the possession of "old brass" which seems to bring them nearer to the great men who years ago laid the foundations on which present-day advance has been built. [Illustration: FIG. 86.--A HANDSOME BRONZE BAROMETER.] Engineers have been very skilful in creating models of engines and machinery with which they have been familiar, and in reproducing in miniature replicas of noted engines which have been used for practical purposes. These little models, some of which were made more than a hundred years ago, in days when steam power was but in its infancy, have been very valuable to engineers to-day, in that they provide them with actual models of old-time engines, the details of construction of which might otherwise have been lost. In one of the museums at South Kensington there are many of these scientific and mechanical models in brass, some of them working on the penny-in-the-slot principle, so that visitors can by the expenditure of a few coppers set in motion any machine they are interested in, and so judge of the actual effects of old-time inventions as illustrated by models which have been made to scale. In addition to working models of large objects there are some remarkably small models which are stored and treasured by collectors. Some are so small and minute, although perfect in every detail, that it is difficult to understand how the worker in brass even if he had been a jeweller and accustomed to fashion the settings of small stones could so accurately have produced such tiny machines. It is said that the smallest engine in the world, a beautiful piece of metal-work, owned by an American collector, stands on a ten-cent piece! Yet remarkable as it may seem, when connected with an electric power cable of very small calibre the engine starts off as if it were a full-size horizontal engine. The chief materials used in the construction are copper and brass, although the band of the fly-wheel is of solid gold. So small is this little engine that its measurements are all taken in sixty-fourths of an inch. Thus the diameter of the fly-wheel, practically the largest piece of mechanism in the construction of the engine, is 28/64 in., and the fly-wheel band only 7/64 in. The valve rod is only 1/64 in., and the outside diameter of the cylinder 12/64 in.; completed, standing on the small coin referred to, the engine weighs 3 dwt., a truly remarkable work of metallic art. XVIII ENAMELS ON COPPER