22 THREE CRUISES OF THE " BLAKE." 



On hauling in, the propeller of the cup screws down, by the 

 resistance of the water, until the upper thread of the hub clears 

 the lower thread of the corresponding screw on the shaft, when 

 the propeller drops on the screw-cap ; the lugs R, it, clutch into 

 the slots U, U, and the screw-cap is screwed down until it 

 touches the upper valve, which keeps both valves closed. The 

 screw-cap is found screwed down so tight in coming out of the 

 water that it can be set no tighter without endangering the 

 thread. 



The tests to which the water-cup has been submitted show 

 that it closes in a depth of about ten to fifteen fathoms, and then 

 remains hermetically sealed. For serial lines the water-bottles 

 and thermometers were not sent down on the sounding-line, but 

 a stronger steel cord, three eighths of an inch in circumfer- 

 ence, was used, to which the thermometers and bottles were 

 attached. 



The annexed sketches of Sigsbee's water-bottle (Figs. 17, 18) 

 will interest those who have used the older apparatus for ob- 

 taining water from great depth. The method of closing the 

 valves is entirely different from that employed by other hydro- 

 graphers. 



Fig. 17 gives a view of Sigsbee's water-bottle, seen facing 

 the frame of the propeller (^9), by which the valves are 

 closed. 



Fig. 18 shows a section of the same bottle, and Fig. 19 the 

 mode of attaching it to the steel rope by means of a spring 

 devised by Lieutenant-Commander Sigsbee. This is done in 

 an instant, and the bottles are firmly held in place by the 

 double spring holding the rope at two points. The same mode 

 of attachment has been adopted for securing the thermometers 

 (Fig. 20) to the line or wire with the least possible delay, and 

 for their easy detachment in place of the clumsy and tedious 

 process of tying and untying them when a serial line of temper- 

 atures is to be made. 



There was no attempt on our trips to make any chemical ex- 

 amination of the water brought up from different depths. The 

 small size of the vessel made a chemical laboratory out of the 

 question, and it seems more feasible for this purpose to establish 



