Scientific American Supplement, No. 623, page 59 by Various Authors
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pplies this stove is vertical and is mounted upon four wheels. It is jacketed with wood, and is provided with a water level, two gauge cocks, a pressure gauge, two spring safety valves, a steam cock provided with a rubber tube that connects with that of the stove, an ash pan, and a smoke stack. In the rear there are two cylindrical water reservoirs that communicate with each other, and are designed to feed the boiler through an injector. Beneath these reservoirs there is a fuel box. In front there is a seat whose box serves to hold tools and various other objects.--_La Nature._
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AN ELECTRICAL GOVERNOR.
We abstract the following from a paper on electric lighting by Prof. J.A. Fleeming, read before the Iron and Steel Institute, Manchester. The illustration is from Engineering.
[Illustration: ELECTRICAL GOVERNOR.]
One of the questions which most frequently occurs in reference to mill and factory lighting is whether the factory engines can be used to run the dynamo. As a broad, general rule, there can be no question that the best results are obtained by using a separate dynamo engine, controlled by a good governor, set apart for that purpose. With an ordinary shunt dynamo, the speed ought not to vary more than 2 or 3 per cent. of its normal value on either side of that value. Hence, if a dynamo has a normal speed of 1,000, it should certainly not vary over a greater range than from 970 to 980 to 1,020 to 1,030. In many cases there may be shafting from which the necessary power can be taken, and of which the speed is variable only within these limits. There are several devices by which it has been found possible to enable a dynamo to maintain a constant electromotive force, even if the speed of rotation varies over considerable limits. One of these is that (see illustration) due to Messrs. Trotter & Ravenshaw, and applicable to shunt or series machines.
In the circuit of the field magnet is placed a variable resistance. This resistance is thrown in o