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May, 1909 not be moved too rapidiy and so in- jure the rheostat. Another method would be by means of only one motor, series wound and fitted with electric brake, which would come into action as soon as the cur- rent is cut out. The necessary start- ing and regulating resistance would be actuated by the steering wheel and differential gears in the previous method. Electric Gear on the Faraday. From this it will be seen that the only alteration necessary to existing gears, would be the replacing of the steam cylinders with a motor, 'and perhaps a slight modification of the differential gear. There are of course other methods which could be applied, but the above appears to meet most fully the requirements, the speed reg- ulation of the motor could be varied from a few revolutions to full speed, and there would be no tendency for the motor to overrun, as the armature current would be reduced. gradually and the motor. stop, when the position of the rudder corresponded with the position of the steering wheel; there would be no sudden shocks to the mo- fOr Or gear; a 'compatatively small motor could be fitted, as the full load would never be required for more than one to one and one-half minutes, and in ordinary working for very much shorter periods. The motor genera- tor could be made to take up.very little space, as it could naturally run at a high speed, and it is doubtful if the first cost would be much more than that of a steam engine with double cylinders, and steam and ex- haust pipes. The gear would be much more silent and efficient. In a paper read by Alex. Siemens, M Inst. C. E., on Sept. 20, 1899, be- fore the British Association, he ex- plained an electrical steering gear on Steamship Faraday, which gave com- plete satisfaction. A shunt motor turned the shaft of the steering gear backwards or forwards by means of electric clutches actuated from the bridge, and the current was interrupt- ed by the rudder head, getting a new impulse from bridge when required to Move again; an indicator showed the quartermaster the position of the rud- der, and the contact apparatus was in the shape of a small steering wheel as usually fitted in the wheel house. Operation of the Windlass. The windlass offers certain difficul- ties to motor drive, but probably none which could not be overcome, and When the comparatively short time TAE MaRINE REVIEW that it is in use and the distance it is from the' main boilers is borne in mind, it is evidently suited for elec- tric driving. The motor would have to be of ample B. H. P, to deal with the heaviest load, be reversible, have heavy starting torque and variable speed; these are common conditions which are fulfilled in everyday prac- tice. The principal objections against electrically driven capstans is that the motor could not be made to run slow- ly and be brought to a standstill when the strain became too great in the same way as can be done by a steam engine. In regard to this, when there is so little steam behind the engine that it can be brought up by the strain on the anchor, it cannot be exerting any great power. On the other hand, if the engine were running full speed and exerting its full power and was suddenly brought up by the strain on the cable, something would be very likely to give away. To overcome such an objection, however, there could be a friction clutch adjusted by means of a spring and hand wheel with an indicator, arranged to | be worked near the control gear wheel, so that the motor could be started on the slow speed and the friction clutch set to a predetermined position on the indicator corresponding to the po- sition of the speed regulator; by this means, if the strain became too great for the motor to deal with at the speed it was running, the clutch would slip, the motor could then be put on a higher speed and the clutch tight- ened to correspond with the speed. This arrangement would prevent any undue strain coming on the motor suddenly and overcome the difficulty of a circuit breaker coming out at an inopportune moment. A circuit break- er should be fitted to come out at Say double the full power of the motor; this would also act as a preventative to too heavy a strain coming on the cables. If the motor applied was of the same B. H. P. for a given size' of windlass as the usual steam engine, it would as naturally cope with the work it had to do; the maximum time for running at full load would be so short that the motor would not require to be of excessive size and could be ar- ranged to run at comparatively slow speed with a wide speed variation. Refrigerating Compressors on Cunard Liners. As an illustration of the flexibility and adaptability of motor drive, mo- tors designed and manufactured by the author's firm for the Liverpool Refrigeration Co., for driving refriger- 77 ator compressors on the steamships Mauretania and Lusitania may be in- stanced. The principal conditions were that they must be absolutely silent, the speed variation was to be as flex- ible as a steam engine between 40 and 110 revolutions. ~The starting torque was to be ample to overcome the gas compression without a by pass, the Starting and speed regulation was to be achieved by means of a hand wheel, - power developed 40 B. H. P. It was at first proposed to have a normal slow speed motor driving through ma- chine cut worm gear, but on further consideration, it was decided that this gear would not be silent as soon as there was any wear, the space re- quired was too great and the cost of gun-metal machine-cut gear for the power required at the slow speed was exceedingly high. The next proposal, and the one adopted, was to make the motors suitable for coupling direct on to the compressor shafts and to de- velop the required B. H. P. at the revolutions specified. The motors were designed with 12 poles and a comparatively large diameter of arm- ature, to give the required torque; as the power at the higher speed was approximately double that of the lower speed, it was decided to fit two commutators and a double wind- ing at the armature; so that for the first variation of speed from 40 to ~ 75 revolutions per minute the wind- ings were in series, and from 75 to 110 revolutions per msute they were in parallel. The intermediate speeds were varied by means of shunt re- sistance. The starting and regulating gear was specially designed to meet the requirements, and completely ful- filled all the conditions. It is operated by means of a hand wheel, the first. steps cut out the resistance with the armatures in series, and by gradually moving the wheel, the shunt resistance is inserted with corresponding in- crease in revolutions up to 75, when by moving it sharply across'a short space, the armatures are put in par- allel and the shunt resistance cut out; on moving the wheel still fur- ther, the resistance is again inserted and the speed regulated to 110 revo- lutions; a locking device is fitted, so that if the D. P. switch is opened it cannot be closed until the handwheel is brought back to starting position. An engraved dial is fitted giving full. instructions. These plants have been at work some time now and have ap- | parently given every satisfaction. Various Uses of Electricity. The many and varied uses to which