146 THE GYROSCOPE POR MARINE PURPOSES. "" 



ing ships than any other. His gyroscope is of the passive type. He is 

 a practical engineer, and at first called to his assistance a number of other 

 engineers and mathematicians and designed the first machine. The work- 

 ing drawings of one of these machines are of interest; they are presented 

 as follows: — Plate 48 is a plan, Plate 49 is a forward elevation, and Fig. 8, 

 Plate 50, a side elevation. Plate 51 shows the complete machine as it was 

 installed on board the Silvanna. 



In Germany, in 1909, Engineer Dr. Frahm had succeeded in over- 

 coming one of the reasons for eliminating the water chambers from the old 

 English men-of-war — that was the noise of the hundreds of tons of water 

 rushing from side to side, which is said to have been intolerable — by using 

 an inverted siphon. The trouble with this arrangement is that the cen- 

 tral opening has to be of such a character as to cause the movement of the 

 water to be synchronous with the boat's period; that is, if in addition to 

 the simple gravitational factor of the water the kinetic energy of the rushing 

 water is to be utilized; while the boat in still water has a fairly uniform 

 period and the movement of the water in the arrangement can be made to 

 conform to a given period, in rough seas, however, the boat is not periodic, 

 varying a great deal. I have seen automatic diagrams of rolling where 

 the period varied from seven seconds to seventeen seconds. Now when 

 the flow of this great quantity of water gets out of synchronism it becomes 

 a menace, and makes the boat roll more and behave worse. Some rolling 

 diagrams are shown in Fig. 10, Plate 50. 



The eminent engineer. Sir John I. Thornycroft of England, did much 

 valuable work in attempts to overcome the last-named difficulty. He 

 placed a great moving weight on a vertical axis which could move as a 

 pendulum in the hold of the ship. An equipment of hydraulic apparatus 

 was provided for swinging this weight from side to side (see Plate 52). By 

 this means the center of gravity of the ship could be changed at will. The 

 weight was about 5 per cent, of the total displacement of the ship, but it 

 was governed by the controlling apparatus mentioned above, in such a 

 way that he succeeded admirably in anticipating all the needs of the ship 

 up to the capacity afforded by this moving weight. The weight had the 

 power of tilting the ship just 2 degrees either side of the vertical when swung 

 to its extreme lateral positions. In sea trials of this arrangement, Sir 

 William White states that it reduced 18 degrees of roll to 9 degrees. To 

 eliminate wind and weather conditions the boat was made to sweep through 

 an entire great circle in heavy seas. This was the first attempt to steady 

 a ship by a controlled reactionary force. The difficulties encountered 

 with this, the water tanks and all other gravitational methods, are that 



