173 BULLETIN OF THE 



other ideas were incorporated with the original plan. From the draw- 

 ings a machine for experimental purposes was made in the winter of 

 1874-5. The new machine was used for three years on board the 

 Coast Survey Steamer " Blake," the vessel being under my command, 

 and engaged in deep-sea work. As we had previously used the original 

 machine for six months, opportunity was had of comparing the relative 

 merits of the two machines. Some faults, arising from bad mechanical 

 arrangements, had first to be rectified in the new machine, after which, 

 even under the most unfavorable circumstances of wind, sea, and cur- 

 rent, it performed as I had wished. In the first form of Sir William 

 Thomson's machine, or rather in its somewhat modified form as used 

 by Captain Belknap, there was simply the reel and register, as shown 

 in my drawings, and in the rear of the reel a small pulley connected 

 tangentically with a scale. Over the friction score of the reel, and thence 

 around the score of the pulley, a single part of an endless friction line 

 was taken, and the scales showed the amount of resistance applied to 

 the reel while the sinker was descending. The wire was payed out 

 directly from the reel into the water. (See the appended sketch, copied 

 from Captain Belknap's book.) To a later form of his machine the in- 

 ventor had added a reeling-in pulley and a swivel or castor pulley, both 

 of which are improvements, and have been adopted by me in designing a 

 new machine. His pulleys arc of different construction and arrangement 

 from those shown in my drawing, but in both cases they serve the same 

 purpose. (See Sir William Thomson's pamphlet on the subject of his 

 machine.) The improvements which I have endeavored to effect lie 

 chiefly in the employment of a peculiar kind of accumulator, and its 

 adaptation to the various uses of accumulator, dynamometer, brake, 

 correct register, and governor. 



I think I may state, after four years of experience in deep-sea sound- 

 ing with wire, in a small steamer, that the value of the improvements 

 warrant their extra cost ; and I would offer the results accomplished as 

 evidence of the correctness of my assumption. 



In reeling in, the new machine has the advantage at all times. In 

 paying out, in perfectly calm weather there is little advantage gained 

 over the old machine ; but when there is any motion to the vessel the 

 gain is very great for the new machine, while in ease of manipulation 

 the advantage is always most decidedly in favor of the latter. 



With the experimental machine between twelve and fifteen hundred 

 soundings have been taken, the original springs being still in use, and 

 no repairs having been necessary in any part of the appai'atus. 



