Dr. C. W. Siemens. 



[June 15, 



the resistance coil to assume the temperature of the water, and after 

 adjusting the temperature of the water around the comparison coil, it 

 was allowed to stand five minutes before the final reading was taken. 



The rolling of the vessel affected the mirror so as to throw the 

 light about 5° on each side of the zero point when the circuit was 

 open, and nearly the same when closed ; but as the deflection was the 

 same on either side it was easy to determine the middle point. While 

 at work in the stream it was necessary to work the engine in order to 

 keep the wire vertical. The jar of the engine, however, affected the 

 mirror to such a degree that readings could only be taken when the 

 engine was stopped. 



The Tables I, II, III, IV give the results of the several lowerings. 



I. 



II. 



Depth, in 

 fathoms. 



Reading of 

 attached 

 thermometer 

 coil. 



Reading of 

 Miller-Casella 

 thermometer. 



Depth in 

 fathoms. 



Heading of 

 attached 

 thermometer 

 coil. 







Reading of 

 Miller-Casella 

 thermometer. 



Surface 

 5 

 10 

 20 

 30 

 30 



81-5 



81 -5 



76-5 



70-25 



69-5 



68-75 



81-5 

 81-5 

 76-5 

 69-5 

 69 



68-75 



Surface 

 30 

 50 

 75 



81-5 

 68-5 

 65 -25 

 60 



81-5 

 65 



III. 



IY. 



Surface 



30 



50 



75 

 100 

 150 

 200 



83-5 

 68 



65 -25 



60-75 



56 



51 



47 



83-5 



54 

 47 



Surface 

 30 

 50 

 75 



200 



84-5 

 81 



75 -5 

 61 -75 



49-5 



84-5 

 80 



49-75 



On August 10th the " Blake " left Hampton Roads, steaming to 

 the eastward until reaching the meridian of 74° 30' W., when a 

 sounding was taken, giving a depth of 1,024 fathoms. A serial was 

 taken to a depth of 400 fathoms with two Miller-Casella thermo- 

 meters, which had been carefully compared with the standard and 

 found to agree at different temperatures. Immediately after the 

 serial with the thermometers the insulated cable was lowered into the 

 sea, and the temperature, by the galvanometer and comparison coil, 

 recorded for the same depths as taken in the first serial. Five minutes 

 was allowed at 5 and 10 fathoms, but there was no deflection of the 



