156 BULLETIN OF THE 



the work. The scheme has been stated in my volume on " Deep-Sea 

 Sounding and Dredging," (p. 145, foot-note,) as follows : — 



'• Our plan is to trap the specimens by giving to a cylinder, covered 

 with gauze at the upper end and having a flap valve at the lower end, 

 a rapid vertical descent between any two depths, as may be desired ; 

 the valve during such descent to keep open, but to remain closed dur- 

 ing the processes of lowering and hauling back with the rope. An idea 

 of what it is intended to eftect may be stated briefly thus : — Specimens 

 are to be obtained between the intermediate depths a and h. The for- 

 mer being the uppermost. With the apparatus in position, there is at a 

 the cylinder suspended from a friction clamp in such a way that the 

 weight of the cylinder and its frame keeps the valve closed ; at h there 

 is a friction buffer. Everything being ready, a small weight or messenger 

 is sent down, which on striking the clamp disengages the latter and also 

 the cylinder, when messenger, clamp, and cylinder descend by their own 

 weight to h, with the valve open during the passage. When the cylinder- 

 frame strikes the buffer at h, the valve is thereupon closed, and it is kept 

 closed thereafter by the weight of the messenger, clamp, and cylinder. 

 The friction buffer, which is four inches long, may be regulated on board 

 to give as many feet of cushioning as desired." 



The following detailed description refers to the accompanying plate. 



The copper cylinder A, riveted to the wrought-iron frame B, has a 

 flap or clapper valve, C, opening inwards and fastened to the inner arms 

 of the lever D D, the latter pivoting at E. The upper end of the cylin- 

 der is covered with the removable wire sieve F (GO wires to the inch), 

 and inside the cylinder are the wire sieve G (27 wires to the inch) and 

 the wire funnel or trap H (27 wires to the inch). 



The steel wire rope on which the cylinder travels is placed in the 

 loops I T, at the upper and lower extremities of the frame, and is re- 

 tained therein by the screw-bolts J J. 



The friction clamj:) is composed of the frame K, the two sliding chocks 

 L and M, the adjusting screw N, the guide screws 0, and the eccen- 

 tric tumbler P. 



The friction hyffer is composed of the frame Q, the two sliding chocks 

 R and S, the adjusting screw T, the steel compression spring U, work- 

 ing in a chamber, and the regulating screw V. The bearing faces of the 

 two sliding chocks are corrugated, and the inward movement of each 

 chock is limited by a stud forming part of the frame and fitting loosely 

 within a slot in the chock. In clamping the buffer to the rope, the 

 chock R is always screwed in until stopped by its stud ; the steel rope 



