2 74 



SCIENCE. 



[Vol. XIV. No. 350 



-pieces being the softest possible cast iron. The magnets and the 

 pole-pieces form a solid frame, being held together by nuts on 

 -the tapped ends of the magnets. The armature, which is of the 

 Gramme type, is supported by brackets of brass bolted to the pole- 

 pieces, and the shaft runs in phosphor-bronze bearings fitted to the 

 brackets. The armature is made of annealed wrought-iron wire 

 ■supported by a three-armed spider of brass. 



The brush arrangement is of improved construction, original 

 -with the designer, and enables the tension of the brushes to be ad- 

 justed without disturbing the setting of the same, and without ex- 

 posing the attendant to shocks from the machine. This is effected 

 by an insulated thumb-screw, — aside from the thumb-screw that 

 holds the brushes, — which clamps the brush-holders to the brush- 

 pin. The rocker-arm is also movable. The cables from the 

 .brushes are carried to a board on top of the machine, on which are 



two horse-power, and, being very compact, occupies a floor-space 

 of only ten by nineteen inches, with a height of twelve inches. 



The armature is of the Gramme ring type, and the pulley end of 

 the shaft has its bearing in the neutral part of the field-magnet. 

 The shaft is of English tool steel of the best quality, the bearings 

 are ground true on dead centres, and the armature is so attached 

 as to practically constitute a portion of it, avoiding all danger of 

 loosening, — a point of importance in this class of machinery. Ball 

 bearings are used, admitting of self-alignment. They are made of 

 phosphor-bronze, hand-reamed, and of considerable length, to give 

 an even bearing surface and prevent all tendency to heat. The 

 commutator sections are of drop-forged copper, hard, and of 

 almost pure metal. The commutator is attached to the armature 

 in a novel manner, and can be renewed without disturbing the 

 armature wires. 



.1 . .,1 . ii 



iiii , ,,',ii'i''/iii'/,i',i,ii 



CINCINNATI ELECTRIC ENGINE C(JM1'ANV'S MOTOR. 



■ placed the terminals ; also a switch for short-circuiting the field- 

 coils, in case it is desired to " paralyze " the machine while run- 

 ning. Thus the switch and terminals are always in sight, and can 



. be attended to at once, if necessary. 



A remarkable feature of this dynamo is that it requires exceed- 

 ingly small floor-space for its capacity, — a feature of great value 

 when the space is limited, as on board of ships, etc. The floor- 

 space required for a twelve-light dynamo is only twenty-four by 

 twenty-four inches. 



A New Constant-Current Electric Motor. 



The electric motor shown in the accompanying illustration is 

 one of a series manufactured and placed on the market by the 

 Electric Engine Company of Cincinnati. It is intended to run on a 

 •constant-current or arc-light circuit, has a maximum capacity of 



The armature is accurately adjusted to a running balance, and 

 provided with means for forced ventilation. The ordinary rocker- 

 arm supporting the brush-holder has been dispensed with, thus 

 rendering the important parts more readily accessible. 



The governor, the construction of which is shown in the figure, 

 maintains the speed constant under all variations of load from zero 

 to the full designed load of the machine, and is remarkably simple, 

 having but one wearing point. It regulates solely by variation of 

 pressure, practically eliminating motion and wear : hence it has 

 great durability and sensitiveness. 



For constant potential circuits, this company manufactures 

 motors of similar design, but differing in detail. As they regulate 

 automatically, they do not require governors. These are made for 

 standard potentials of no, 220, and 550 volts, though they may be 

 made for any specified voltage. 



