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 KR, R, 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 
serew-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 (p), by which the valves are 
closed. i 
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 seeuring 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 chemieal 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 
