180 MODEL EXPERIMENTS AND SPEED TRIALS, ETC. 



pair of the United States Navy, for the use of Naval Constructor D. W. Taylor in investi- 

 gations of the torque actually received from waves by a large series of models with different 

 form lines. Under the peculiar conditions of the operation of the gyro stabilizer, which, it 

 may be stated here, are probably unique, the model may be held free from motion while it 

 is receiving heavy torques, and the amount and direction of these torques may be measured 

 by the amount and direction of the precession angles of the gyro. 



"The recording mechanism is also mounted upon the model together with a model gyro 

 roll recorder, which was shown in my paper read before this body last year, the actual roll 

 record and movements of the stabilizing gyro frames being recorded side-and-side on the 

 same tape. In this manner the impingement of the waves upon the model, which would cause 

 it to roll excessively and through wide angles, really causes vigorous and wide angular 

 movements of the precession frames of the gyro stabilizer only ; but the ship's model does not 

 move, giving at once a beautiful opportunity to measure the torque actually received by the 

 model from waves of various heights, periods and angles to the model, and at the same time 

 beautifully demonstrating the capacity of a gyro stabilizer to very completely prevent rolling, 

 which without the stabilizer would be excessive and which in a full-sized ship would render 

 the ship uninhabitable. 



"In Plate 115 the control, which has finally been standardized, is shown to the right 

 and operates entirely by angular velocity of roll of the model. By this device all difficulties 

 with wind list, or permanent list, are done away with ; that is, the particular position as to the 

 vertical about which the ship tends to roll is a matter of entire indifference to this form of 

 control ; it is found to operate at equal efficiencies with the ship in any position of perma- 

 nent wind list. 



"I might call your attention to one interesting feature of Plate 117, which you have 

 before you, and that is the wave-maker. Heretofore on roll-pendulums, and in similar ex- 

 periments, various methods for using springs in imparting wave momentum have been used 

 which were open to objections, but here is a wave-maker which is practically free from such 

 objections. You will notice in the foreground a cast-iron roller which rolls back and forth 

 on a platform, giving an impressed moment on the pendulum which is perfectly sinuous and 

 which gets very close to the absolute theoretical requirement; this is especially true, as you 

 will see on Plate 118, as the pitman operating this wave-maker has some twenty times the 

 radius of the crank, so that the effect of the angular component of the wave-maker is almost 

 wholly eliminated. The recording apparatus is also shown on this last plate, by which we 

 were able to record simultaneously the waves and the oscillations of the ship. 



"Plate 118 shows the method of recording and includes simultaneous diagrams of the 

 wave-maker and the resulting oscillations of the pendulum. The simultaneous diagrams form 

 a large part of the work but are not referred to in the present figures. 



"Plate 116 shows the general disposition of the weights with which the cycloid pendu- 

 lum was loaded. 



"I thank you for your kind attention." 



