THREE CRUISES OF THE BLAKE 173 



Tortugas. The expedition terminated in a trip from 

 Tortugas to the mouth of the Mississippi, Agassiz and 

 Mr. Garman leaving the ship at New Orleans about the 

 middle of March, 1878. 



In writing from shipboard to Lord Kelvin concerning 

 the working of the new apparatus, Agassiz says : — 



" I know you will be interested to hear of the results 

 of the working of the wire for sounding and of the steel 

 rope for dredging. . . . Captain Sigsbee's machine, a 

 modification of yours, worked to a charm ; and the time 

 occupied in taking a deep sounding is so small that I 

 hope to see the day when all large passenger steamers 

 will have a wire sounding machine, and we shall hear 

 nothing more of running ashore because no observations 

 could be had a few days before reaching the coast. But 

 of course our deep-sea hydrography must all be done 

 over with wire, for with the rope soundings no accuracy 

 can be obtained ; of this we have had several examples 

 during the present cruise while crossing old lines of 

 soundings run in the antiquated method. I could not 

 help contrasting our soundings — losing a fifty-pound 

 shot by the detacher and bringing up samples of the bot- 

 tom in so short a time as sometimes twenty seconds for 

 a hundred fathoms ! with those of Challenger expending 

 three to four hundred pounds at each cast, and occupy- 

 ing at least six to eight times the length of time in 

 bringing up their cup and thermometers. We could al- 

 ways detect instantly the moment the shot struck the 

 ground, which is more, as you well know, than can be 

 done by the rope and weights in deep water. . . . 



" The steel rope we used in dredging has also proved 

 a great success ; in fact I do not see how with a small 



