64 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [62], 



SiaSBEB'S DETACHER (PLATE XXXIII.) 



[Used in counectioa -with a modiiication of Captaiu Belknap's sounding cylinder 



No. 2.] 



The first device for detaching the sinker and bringing up a specimen 

 of the bottom in deep-sea sounding was the invention of Passed Mid- 

 shipman John M. Brooke, U. S. IsT., about 1852-'53, It consisted of a 

 small iron rod carrying a trigger at the upper end, and a small tube at 

 the other extremity, in which several goose-quills were placed for bring- 

 ing up bottom specimens. The sinkers were much like those of the 

 present day; a shot with a hole through it. 



To prepare for a sounding the line was bent to the trigger, the goose- 

 quills were adjusted in the tube, the sounding rod was inserted in the 

 hole through the sinker, the slings were passed under the sinker and 

 hooked to the trigger, which sustained the weight until the sounding 

 line was slackened by its striking the bottom, when the trigger capsized 

 by its own weight, the slings slipped oft" and the sinker was released. 



Sands' cup was the nest device brought into use in the Navy and 

 Coast Survey, but Brooke's apparatus was in general use until the 

 " Hydra " machine as improved hy Staff Commander Baillie, R. N., was 

 adopted. 



The Fitzgerald machine w^as used to some extent in the British navy. 



The next marked improvement is due to Capfc. Geo. E. Belknap, 

 U. S. iSi., who while in command of the U. S. S. Tuscarora made the 

 most remarkable series of deep-sea soundings on record. Following 

 in h?s footsteps Lieut.-Comdr. C. B. Sigsbee, U. S. IST,, made some modi- 

 fications in the Belknap cylinder, and added to it a detaching trigger 

 of his own, reducing it to its present form as shown in the plate. 



If the various types of sounding cylinders and detachers made since 

 Brooke's invention became known were examined, it would be seen that 

 they are all modifications of his system, as in sounding with wire all 

 recent improvements in that direction have been modifications of Sir 

 William Thompson's admirable system. 



NOMKKCLATURE. 

 a. Cylinder. 

 h. Screw joint. 

 c c. Upper and lower guide stem. 



d. Cylindrical ring. 



e. Valve seat. 



/. Poppet Talve. 

 g. Valve stem. 

 h. Spiral valve spring, 

 i. Hollow cone. 

 j. Perforated plate, 

 h. Swivel. 

 I. Pawl, 

 m. Tumbler. 

 n. Spring. 



2). Apertures for escape of water, 

 q. Sinker. 

 r. Iron wire bail. 



