48 
CRUISE OF H.M.S. CHALLENGER. 
rod with three radiating ribs to strengthen it, and to 
act as a guide for a brass cylinder which incloses the 
water. At the bottom, and halfway down the radiating 
ribs, are two finely ground seatings, and the brass 
cylinder is so arranged that its upper and lower sur- 
faces fit with great accuracy on these seatings, thus 
inclosing anything that may happen to be between 
them. At the top of the rod is a brass tumbler, with 
a slit in it ; to this tumbler is attached a lanyard to 
fasten the bottle to the sounding line, and over the 
slit of the tumbler is placed the bight of a piece of 
small line (the ends of which are secured to the 
cylinder), by which the cylinder is kept suspended 
above the seating while the bottle is descending, and 
being in this position quite clear of the radiating 
ribs, it allows the water to pass freely through it. 
Directly the strain is released on the sounding 
line above, through the bottle reaching the bottom, 
the tumbler falls over, pushing off the line that sus- 
pends the cylinder, leaving it free to fall on the two 
seatings, and thus effectually inclosing a specimen of 
the bottom water. A tap is arranged at the lower 
end to facilitate the emptying of the bottle when 
again on board. 
Other bottles (Fig. 6), but of different construction, 
for carrying out similar results were employed with 
equal success ; they consisted usually of a brass tube 
about 3 inches in diameter and from 2 to 3 feet in 
length, fitted at either end with stop-cocks connected 
