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December, 1909 better to such a joint control than the turbine. That would be very ad- vantageous. President Taylor: Mr. McFarland, we would be glad to hear from you on. this subject. W. M.. McFarland: I am in the same position as a good many of the other gentlemen, Mr... 'Chiarman. -[ did see the paper before I came here, but have not had time to read it care- fully, and knowing Mr. Emmet's em- inent ability, I would naturally as- sume that anything he would put for- ward would. be correct, so that I have no comments to make on the paper at all. President 'Taylor: This subject opens up a wide field. and I trust you gentlemen will take advantage of this opportunity for discussion. If there is any gentleman present who will say something, we will be glad to. hear from him. Mr. E. A. Sperry. E. <A. Sperry: An engineering friend of mine took exception to one sentence on page four of Mr. Em- met's paper, where the following statement is made: "These results it will accomplish without the intro- duction of any feature which can be considered problematical," illustrating that by land turbines and land prac- tice. My friend also called my attention to the figures on plates 1 and 5, and the excessive speed there indicated. The remark was made that these large masses running at very high speeds, would introduce a certain gyroscopic phenomenon, which might become very problematical. I wish to Say that this phenomenon is one that I have investigated somewhat, and I would like to add my testimony that the remark made by Mr. Emmet in his paper is correct, the working of the turbines in this way does not in- troduce any gyroscopic motion, no matter what speed or weight are in- volved, so that I think this clause has been introduced advisedly. Mr. Parker H. Kimball. Parker H. Kimball: I wish to ask Mr. Emmet in reference to page four, where he says:. "The voltage is low and the arrangement of generator and motor constitutes the simplest known means of electrical power transmission. With such apparatus insulation trouble or mechanical trou- ble is practically unknown, and there is no other form of mechanism which can accomplish such results with equal simplicity and certainty." I ask what is the maximum voltage TAE Marine REVIEW used on the combination drive? It is stated for the full electric, but not for the combination; also, what are the approximate frequencies used? President Taylor: Is there any other gentleman who desires to dis- cuss the paper? If not, I will ask Mr. Emmet to close the discussion. Handling From the Bridge. Mr. Emmet: The first subject rais- ed is that of handling from the bridge. I will say that this particu- lar scheme, that this paper mentions, offers no special advantage for hand- ling from the bridge, because of the result of interconnection of generator unit and the motors. The Curtis drive could 'be very handled from the bridge, just as we handle it from our speed generators, more easily than to have it handled. from the engine room, and this could also. be. handled from the since itis ai Curtis . tufbine; but to make these changes for reversing and all that, it would be necessary to pro- vade means . for shutting off - the steam, and while naturally that would be taken care of by the valve--you see in the Curtis turbine we use in- dividual. valves for admission, these valves are controlled by a cam shaft, which is moved by steam or hydrau- lic means, generally by steam. This opening or closing of valves can 'be worked by any engine room telegraph method. It would be easy, as we do in the controlling of a locomotive, to. work all the switches necessary by electric means. In point of fact, the propulsion of a ship, is about equiva-. lent to the propulsion and operation necessary in the driving of one of the New' York Central locomotives, and 40 or 50 of them are doing daily service up and down the road,--all the high resistance and switch mech- anism is entirely away from the engineer, and he pulls the lever one way or the other, and it might as well be a mile away as 10 ft. away, the result is the same. He does not know what is happening when. he pulls the lever, he knows the machine turns around and goes the other way. That could be accomplished in this apparatus and could be accomplished in the straight Curtis drive, with more simplicity, and with very little difficulty it could be accomplished in the Parsons drive. Variations in Speed. As to the variation in speed--there is one thing about this which some of you may not have understood-- this method I am proposing' is not straight. easily © bridge, 495 a means of electrical speed variation. Everything remains fixed. We do not make any gradations of speed by electrical means. The only speed change made is in changing the number of poles in the motor for certain low speed conditions, namely, the cruising speed of the ship. We make an adaptation for the cruising conditions, and that adaptation being made, the ship can be brought to the higher or slowest speed permissible in the apparatus without any change of connection. If you reach the limit of that particular point and want to go to higher speeds, then you make a new adjustment, and then we have another arrangement which enables you to go on up in speed. I cannot give you a very good idea as to the cost of this apparatus, but I can say that we build turbines, have built a large number of turbines of various sizes. Our larger, turbines weigh approximately the same as the generators which they drive, not much difference, a little bit more per- haps. The cost of building these tur- bines which are of the same general type as this is not very different per pound from that of the generators which they drive. Our turbines are similar in construction to the Curtis marine turbines, that is, in the gen- eral character of their construction, and therefore it is easy to see that pound for pound my combination is not very much more expensive to build than straight turbine drive. I will say, roughly; that some of our large turbine apparatus, a great deal of it, I think, throughout the coun- try, is sold somewhere in the neigh- borhood of 20 cents a pound, and the weight of this has been given, and you can figure up somewhere around what it.might cost. However, this being a special thing, and there being .a good deal of special adaptation in connection with it, it might run a good deal higher--I have not figured what it would come to now, but it would probably give you a wrong idea to make it look cheaper than it would be, because it is our aim to make it just cheap enough. Starting with Turbine Cold. Mr. Anderson raised the question - of the valves in connection with that combination drive. Of course, in that scheme we would use for admission separate individual valves to cover certain small gtoups of nozzles. We also might use large throttle valves as well. If the ship was standing still, and that part used, the smaller valves would "be closed.