FIREPROOF PASSENGER STEAMER. 189 



To illustrate the simplicity of large electrical apparatus I will give you an 

 example. The Detroit Edison Company is operating a large substation out in the 

 suburbs of Detroit, without any attendant in it. As a matter of precaution in 

 starting this new type they have so far gone through the form of sending a man there 

 to watch it, to make sure that its automatic functions were operating correctly. 

 The processes of starting that substation, synchronizing it and getting it on to the 

 circuit, and getting it to work, are all accomplished from distant stations, directly 

 and simply. The reason for this possibility is that they are using simple rotation 

 and there is no mechanical functioning which has to be performed. Electrical 

 functions do not need personal contact for their performance. They can be per- 

 formed from a distance, and the mere closing of switches is a very simple matter. 

 The ordinary electric functions performed in a hotel in connection with the annun- 

 ciating systems, and all those things, are often much more complicated than any- 

 thing which it would ever be necessary to do on board ship, and the chances from 

 trouble from one of these little devices in connection with every room in the hotel 

 is as great as that essentially associated with the electric machinery necessary to 

 drive a ship. The fact that it involves large amounts of power makes it less familiar 

 to the ordinary individual, but the simplicity is still there. 



The economy in the application of this method of propulsion to this vessel is 

 a question, in my opinion, much more of the propelling device than of the prime 

 mover, although I have no reason to suppose that the propelling device proposed 

 would not be good. I could imagine that in shallow water there might be some diffi- 

 culties about getting a high efficiency of propulsion, and that conditions of such a 

 character might outweigh advantages in fuel economy incident to the better prime 

 mover, but as to the economy of the prime mover itself there can be no question. 



It will take far less steam than the reciprocating engine which would be used 

 for such a type of vessel. 



One reason for using the side wheels on such vessels I have always understood 

 is the absence of vibration, the vibration of propellers being apt to shake the super- 

 structure. I think in this boat Mr. Donnelly does not have to deal with this ques- 

 tion so much, because it is not a boat upon which people sleep, but with three pro- 

 pellers of high speed I should think that would not be serious, but I personally 

 have no knowledge as to how effective this propeller might be, and suggest it as a 

 subject for interesting discussion. 



The electric design proposed in this paper, which Mr. Donnelly has himself 

 decided upon, is the result of experience with dredges, I understand. The method of 

 control of the speed of the motors is one that is commonly used in various forms 

 of appUcation of induction motors to such things as hoists, and it is done by cutting 

 resistance into the secondary of the motor and so slowing it down without interfering 

 with the continuity of voltage or frequency on the driving circuit. All the methods 

 of electric propulsion which I have proposed have involved a slowing down of the 

 turbine, or in direct current control apparatus a change of voltage, and a control of 

 the speed of the vessels by the turbine. In this case it is proposed to increase the 

 resistance in the rotor^of the motor. Increasing the resistance will slow the motor 



