144 THE GYROSCOPE FOR MARINE PURPOSES. 



roll from the vertical, one-fourth as eflfective at 5 degrees roll, only equaling 

 at 12 degrees roll, and being three times as effective at 18 degrees roll. They 

 are also known to increase materially the resistance, skin friction and 

 motive power required in all weathers. Sir John I. Thornycroft introduced 

 a method of anticipating the rolling by the means of a controlling mechanism 

 compounded of many active features involving a short and a long pendulum, 

 a retarding device and a cataract all organized to co-act; these were 

 operated on the floating link principle, a moving ballast being operated 

 by heavy hydraulic machinery in the hold of the ship. 



It is more than probable that the true engineering significance and 

 the enormous power of the gyroscope were first discerned in this country; 

 that is, observations concerning it were first made here. It happened 

 in this wise. There was in the early history of our Navy a torpedo known 

 as the Howell torpedo, which depended for its action upon the rapid rotation 

 of a fly-wheel. The torpedo was a cigar-shaped craft and amidships there 

 was a steel wheel some 1 6 inches in diameter that was rotated up to about 

 16,000 revolutions per minute. As a matter of fact, the speed of rotation 

 was so great that the ^-inch clearance left round the periphery was 

 taken up by the centrifugal stresses acting upon the elasticity of the steel 

 of the wheel, which was thus utilized as an automatic brake. This wheel 

 was coupled to and served to drive the propellers when spun up. 



We had in America at this early time the forerunner of the present 

 steam turbine, viz., the Dow steam turbine, which was directly connected 

 in such a way as to spin the massive wheel up to 16,000. Mr. Nixon, late 

 of the U. S. Navy, had charge of some attempts at marksmanship with the 

 Howell torpedo. He was anchored out in the bay, a certain distance from 

 the target, and some difficulty was experienced in starting the steam tur- 

 bine. But finally, after quite a lapse of time, the crew succeeded in getting 

 the turbine going and gradually spun the wheel up. You understand it 

 takes considerable time to store energy in a revolving mass and attain this 

 high velocity. After the velocity had been reached and everything was ready, 

 lo and behold! — the ship on which the machinery was located, anchored 

 out in the bay, had turned, the tide having changed, and instead of the 

 torpedo now being pointed at the target, it was found that the target was 

 considerably to one side of the direction in which the torpedo now pointed. 

 Mr. Nixon called upon some of the members of his crew to change the 

 torpedo and point her over toward the target, but they found this difficult. 

 They had no trouble in getting it up, but no amount of effort sufficed to 

 budge it laterally; it would not change its direction. So the lieutenant 

 called for more men. It simply had to come and finally it started slowly 



