SOME GRAPHIC STUDIES OF THE ACTIVE GYRO STABILIZER. 189 



of the wheel would grasp this outside casing and make an automatic brake. This fact was 

 used by Howell years ago with fine effect; he allowed the wheel to swell about 1/32-inch 

 before making its own brake. It is a fact that the size and the weight of the plant are 

 extremely small and its safety is practically perfect. 



As to the matter of stresses in the hull that was inquired about, my observations as to 

 the stresses present were these. We were experimenting with a comparatively large ship, 

 in heavy stonns; toward the latter part of the tests we became very particular and would 

 not go out until it was blowing up strongly and a very heavy sea running, as reported by 

 wireless by the pilot ship standing at sea out of this port. We were also given a consort 

 when we went to sea on these occasions. Many observations were made. We put on jumpers 

 and crawled under the deck and did everything we could to detect the slightest signs of stress 

 or duress in all parts near the plant, but there were no apparent stresses or deformations 

 whatever. We knew exactly what the stabilizing forces were, and when we were holding 

 the ship from beginning to roll she simply rode the sea, and there is no reason why, while 

 riding the sea, the stresses involved should be as large as when rolling. No stresses are 

 caused in the hull by the precession motive forces as the forces themselves are almost 

 zero. In fact, we obtained many checks upon the power of our precession motor, and it 

 was found to be almost nothing when holding the ship. We found mathematically several 

 years ago that the power should be zero when holding the ship against even heavy seas. 

 The tendency to roll is there, but this is taken care of by equal and opposite forces — 

 forces, mind you — the motion is absent. That means zero power. We found that absolutely 

 on our precession motor; it required next to no power; we could turn the steam away 

 down from the boiler pressure of 150 pounds, and when we had 15 pounds of steam on 

 our little precession engine she handled the apparatus perfectly in the heaviest sea. Perhaps 

 this will tell you something of the stresses — you can see that they did not exist from this 

 source ; their amount is perfectly well known and clearly defined, and is extremely low and 

 easily cared for. 



The Chairman : — I am sure you all desire me to extend the thanks of the Society to 

 Mr. Sperry for the amplification of his paper in the extemporaneous remarks which he 

 has made. I do that with pleasure. 



We now come to the last paper on the program. No. 18, entitled "Electric Propulsion 

 on the U. S. S. Jupiter," by Mr. W. L. R. Emmet. 



In presenting his paper, Mr. Emmet reviewed the subjects touched upon in it and 

 related experiences in the operation of the Jupiter. He explained the great economy and 

 practical advantage of the modern high-speed turbine as it might be applied to ships, either 

 through the medium of electrical apparatus, or of gearing. He explained the advantages 

 which electric drive afforded as compared with gearing, and expressed regret that the U. S. 

 Government had not done more to realize the very particular advantages which this method 

 offered in a large warship. 



