48 RECENT PROGRESS WITH THE ACTIVE TYPE 



In stabilizing a ship with the active type of gyro no effort is made to hold the 

 ship exactly vertical. On the contrary, the ship has full freedom in point of list, 

 due either to distribution of load or wind or both. That is, the stabilizer holds the 

 ship from motion, allowing it to take up any natural central position it chooses and 

 to change this position from time to time, as conditions alter. Attempt has been 

 made to show this in Figs. 14 and 15, Plate 35. In the latter the ship was turned 

 back and forth with reference to the wind so as to emphasize the independence of 

 the wind list. This is shown by the wandering line drawn through the center of the 

 oscillations. In Fig. 14 the ship is being stabilized while in the trough of the sea, 

 while in Fig. 15 the ship is brought in and out of the trough of the sea. 



Figs. 16 and 17, Plate 36, show the rolling records while going in the trough of 

 the sea with the gyro "on" and "off" in medium wind. The maximum amplitude is 

 marked at several points on the chart, together with the points where the gyro was 

 thrown "on" and "off." Fig. 16 is brought in as exhibiting one very interesting fea- 

 ture, namely, that the rolling of the ship is always due to an accumulation of indi- 

 vidual wave increments. These are seen to increase quite uniformly from the right 

 to the left when the gyro is thrown "off." 



The thanks of the author are due to the many courtesies received from the 

 owner of this yacht, Mr. H. M. Hanna, Jr., and his officers and crev/. 



DISCUSSION. 



The President : — We will be very glad to hear discussion on this paper entitled, "Re- 

 cent Progress with the Active Type of Gyro-Stabilizer for Ships," by Mr. Elmer A. Sperry, 

 a Member of the Society. 



Mr. K. Orbanowski, Member : — I have had occasion to follow up the development of the 

 anti-rolling tanks of Frahm' in Hamburg, and I am therefore very interested to see what pro- 

 gress the invention of Mr. Sperry has made in this country in the few years since he first 

 undertook this work. 



With Frahm's tanks they had especially satisfactory experiences on big ships and a certain 

 European government undertook about a month's trial in the Atlantic with a steamer of about 

 3,000 tons under all possible conditions and directions of sea and wind. The result which it 

 reached at the end of a month's experiment was that the rolling in the average decreased by 

 about 50 per cent. 



We are impressed here today with the success of this invention by Mr. Sperry for smaller 

 vessels, and there seems to be in this country great faith in it for the big ships. So I would be 

 much interested to know what Mr. Sperry himself thinks in this respect, what dimensions and 

 weights of stabilizer we may expect to apply for bigger displacements, and if there is a me- 

 chanical possibility of using his invention for the steadying of large ships with the same suc- 

 cess as has been attained with the invention of Mr. Frahm. 



Referring to the advantage of anti-rolling devices for the increase of speed mentioned 



