ACTIVE TYPE OF STABILIZING GYRO. 223 



poses intended, and their value in naval work. Mr. Gillmor is very optimistic, 

 but in my opinion he is not too optimistic. 



Mr. F. I,. Du Bosque, Member of Council (Communicated): — The discovery 

 by Mr. Sperry of a device that will prevent the rolling of ships at sea, which this 

 paper really shows, comes to us with such suddenness and surprise that its effect 

 is not fully realized. 



It seems to me that Mr. Sperry has discovered a new force in so far as its 

 effect upon ships is concerned. The earth's motion and the motion of the heavenly 

 bodies have a precessional movement in the path of their orbits, and a force in a 

 horizontal direction similar to this is exerted by the gyroscope when rotated on 

 a horizontal axis. The amount of the force is dependent upon the speed and weight 

 of the gyroscope and the direction in the horizontal plane is easily controlled. 



Mr. Sperry has determined by experiment and calculation the force exerted 

 by this precessional movement of the gyroscope and is able to decide the size of 

 machine and the speed of rotation required to produce any precessional force. 

 It can easily be conceived, therefore, that when the force required to Ust a vessel 

 to any degree is known, it is possible to install the proper type of gyroscope to 

 prevent this listing action. It must be borne in mind, of course, that the move- 

 ment of the gyroscope to prevent listing must anticipate the listing action and its 

 direction, and Mr. Sperry proposes to accomplish this by instalHng a very sensitive 

 gyroscope pendulum that, acting on suitable devices, cause the main gyroscope 

 to slowly oscillate on its vertical axis in the proper direction at the instant the vessel 

 heels to the slightest degree. It is not likely, therefore, that a vessel can be main- 

 tained in a constant upright position, but undoubtedly the angle of heel will be 

 very small and not sufficient to cause annoyance to passengers. In this respect 

 the gyroscope is undoubtedly superior to rolling tanks that have been experimented 

 with considerably in the past, and it seems to me that the author of the paper has, 

 in a practical and commercially possible way, provided the long-sought-for device 

 that will prevent the annoying rolling of ships. 



Mr. Sperry (Communicated) : — I wish to congratulate both Mr. Frahm and 

 Messrs. Blohm & Voss, who are the owners of the Frahm damping tanks, upon 

 the favor with which their installations have been received. I look upon this 

 effort to damp out part of the rolling of ships, even reducing it to 33 per cent, 

 as Mr. Blohm states at one point in his discussion, as being in the right direction. 

 I believe that our German contemporaries are doing excellent missionary work in 

 educating the public in the use of ships that roll much less than heretofore, and 

 toward ships that in the future will be entirely free from rolling. The full scale 

 trials that have been prosecuted during the present year have ushered in a new 

 era wherein ships will be entirely free from rolling. 



The tanks Mr. Blohm refers to in his discussion are for the purpose of reducing 

 the rolUng, or suppressing it in part, whereas the active type of gyroscope described 



