36 



THREE CRUISES OF THE " BLAKE. 



several operations of lowering, dragging, and hauling back re- 

 mained open ; this cannot be regarded as affording acceptable 

 e\4dence of the habitat of such specimens as were obtained. It 

 became an interesting problem on the " Blake " to determine 

 accurately how far these pelagic forms really extend. Lieu- 

 tenant-Commander Sigsbee contrived a machine intended to 

 furnish means for solving this problem.^ It consisted of a cop- 

 per cylinder to be sent down closed on a collecting expedition 

 to any depth desired, when it was opened by a messenger ; being 



^ Sigsbee's apparatus consists of a cylinder, covered with 

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

 end. The cylinder is heavy enough to acquire a rapid vertical 

 descent between any two depths, — the valve during the descent 

 keeps open, but remains closed during the processes of lowering 

 and hauling back with the rope. An idea of what it is intended 

 to effect may thus be stated briefly : specimens are to be ob- 

 tained between the intermediate depths a and h, the former 

 being the uppermost. "With the apparatus iu 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 mes- 

 senger, clamp, and cylinder descend by their 

 own weight to h, with the valve open dur 



C{ 



ing 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 accompanying 

 sketch of the trap (Fig. 33) explains itself. The 

 copper cylinder A is retained in place by screw- 

 bolts. It is riveted to a wrought-iron frame 

 B, has a flap-valve C, fastened to a long lever 

 D, pivoting at E. The top of the cylinder is 

 covered by a wire sieve, and in addition tliere 

 is a wire-gauze funnel or trap H, inside the 

 cylinder. The cylinder is hung to the friction- 

 clamp K, by an excentric tumbler P, which is 

 released whenever the messenger X strikes it, 

 allowing the messenger, cylinder, and clamp to 

 travel with the valve open till it strikes at the 

 requisite depth the buffer Q. The valve is then 

 closed, the cylinder drawn up, and the contents 

 of the sieves carefullv examined on deck. 



33. — Sigsbee's Gravitating 

 Trap. (Sigsbee.) 



