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conductors on the armature, or to increase the number of field coils, or both. That means a larger machine, and a corresponding increase in cost. In practice, in large plants, with alternating-current machines it has become usual to mount the field magnets on the shaft, and build the armature as a stationary ring in whose air space the field coils revolve. This simplifies the construction of slow-speed, large-output dynamos. Such a machine, however, is not to be had for the modest isolated plant of the farmer with his small water-power. [Illustration: Instantaneous photograph of high-pressure water jet being quenched by buckets of a tangential wheel] [Illustration: A tangential wheel, and a dynamo keyed to the same shaft--the ideal method for generating electricity. The centrifugal governor is included on the same base] Dynamos can be designed for almost any waterwheel speed, and, among small manufacturers especially, there is a disposition to furnish these special machines at little advance in price over their stock machines. Frequently it is merely a matter of changing the winding on a stock machine. The farmer himself, in many cases, can re-wind an old dynamo to fit the speed requirements of a direct-connected drive if the difference is not too great. All that would be necessary to effect this change would be to get the necessary winding data from the manufacturer himself, and proceed with the winding. This data would give the gauge of wire and the number of turns required for each spool of the field magnets; and the gauge of wire and number of turns required for each slot in the armature. The average boy who has studied electricity (and there is something about electricity that makes it closer to the boy's heart than his pet dog) could do this work. The advantages of direct drive are so many that it should be used wherever possible. When direct drive cannot be had, a belt must be used, either from a main shaft, or a countershaft. The belt must be of liberal size, and must be of the "endless" variety--with a scarfed joint. Leather belt lacing, or even the better grades of wire lacing, unless very carefully used, will prove unsatisfactory. The dynamo feels every variation in speed, and this is reflected in the lights. There is nothing quite so annoying as flickering lights. Usually this can be traced to the belt connections. Leather lacing forms a knot which causes the lights to flicker at each revolution o
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