6 THREE CRUISES OF THE " BLAKE." 



provided Avith them, and for them as well as for the " Blake " 

 sounding with wire to any depth has become a matter of daily 

 routine/ 



Commander George E. Belknap, U. S. Navy, while com- 

 manding the U. S. S. " Tuscarora," during her operations in the 

 Pacific Ocean, in 1873, was the first to test thoroughly the 

 Thomson machine by constant use. While it was evident that 

 the machine for sounding by means of wire gave remarkable 

 results as compared with rope-soundings, its success was appa- 

 rently due in a great degree to the intelligence, patience, and 

 skill of Commander Belknap and the officers who assisted him. 

 Commander Belknap had always been forced to reel in the 

 wu-e by hand. Among the plans that presented themselves to 

 Lieutenant-Commander Sigsbee for the improvement of the ma- 

 chine, in order that it might be worked with fewer demands on 

 the watchfulness and ingenuity of those having charge of it, 

 was the interposition of an accumulator on the wdre, between 

 the reel and the sinker, which, by showing the strain on the 

 wire at all times during the reeling in, and by easing the sud- 

 den jerks on the wire" caused by the motion of the ship, would 

 allow of reeling in by steam. A machine for experimental pur- 

 poses was made in the winter of 1874—5, and the new machine 

 (Fig. 3) was used for three years on board the Coast Survey 

 Steamer " Blake," when that vessel was under the command of 

 Lieutenant-Commander Sigsbee, and engaged in deep-sea w^oi-k. 



The following account of the main points of the Sigsbee ma- 

 chine is taken from the inventor's detailed description of the 

 apparatus in the Bulletin of the Museum of Comparative Zool- 

 ogy, and its improvements in " Deep-Sea Dredging : " — 



The reel {A, Figs. 4, 5) should be, for convenience, one 

 fathom in circumference of drum, and should have a friction- 

 score which is V-shaped in cross- section. When the sinker 

 strikes the bottom, the momentum of the reel and its remaining 

 wire requires to be quickly overcome by the resistance of the 



1 But even this excellent sounding the ocean with as great accuracj' as we 



machine may soon be superseded by can ascertain the height of mountains 



Siemens's bathometer, which will en- by a barometer, 

 able us to read on deck the depth of 



