[79] FISHERIES OF THE UNITED STATES. 591 



Navy, constructed a metal case or cylinder for holding the thermome- 

 ter tube, which could be tripped by means of a messenger sent down 

 the wire from the steamer. More recently this same case has been per- 

 fected by Passed Assistant Engineer W. L. Bailie, United States Navy, 

 who has added a clamp at the lower end for attaching it firmly to any 

 part of the sounding wire. 



The examples displayed are of the latest pattern. They consist of a 

 brass tube about 11 inches long and seven-eighths of an inch in diam- 

 eter inside, with slits on two opposite sides 5 J inches long by half an inch 

 wide, through which the mercury and scale of the thermometer can be 

 seen. The lower end of the tube, which is open, is pierced on the sides 

 with four longitudinal rows of three holes each for the freer entrance of 

 water, and terminates on one side in a hook for the suspension of a mes- 

 senger. The clamp for the fixed attachment of the tube to the sound- 

 ing wire is fastened to the upper part of the hook. It consists of a 

 square piece of brass, raised on one side to form a flange or groove, into 

 which a quadrant of an eccentric curve fits snugly against the sounding 

 wire, being controlled by a stiff spring. The upper part of the case is 

 fitted with a "messenger head," designed by Lieutenant Tanner, and 

 consisting of a tube 2 inches long, which screws onto the main tube. It 

 is furnished on top with a perforated screw cap, and has a slot on one 

 side three-fourths of an inch long but of different widths, the upper one- 

 third or slightly more being three-eighths of an inch wide and the lower 

 two-thirds five-eighths of an inch wide, the sides of the slot curving ab- 

 ruptly from the lesser to the greater width, The slip hooks, for the at- 

 tachment of the upper part of the case to the sounding wire during its 

 descent through the water, pass through the slot, are 1£ inches long and 

 project three-fourths of an inch outside. Their exposed portions are 

 curved so that they meet only at the tips, leaving quite an open space 

 within. They are held in place by a brass pin, which passes loosely 

 through their inner ends, and fastens into the sides of the messenger 

 head. A double wire spring, making three turns around the support- 

 ing pin on each side of the hooks, and passing underneath the hooks in 

 front of the pin, forces the former up into the narrower part of the slot, 

 in which they fit snugly and are held closely together. A strong press- 

 ure or blow from above throws them into the broader part of the slot 

 where they readily open. The messenger is an elongate piece of round 

 brass, If inches long by 1 inch in diameter, and is bored with a three- 

 fourths inch hole. It is rounded at both ends and furnished with a bale 

 above for suspending it ; its weight is about 6 ounces. The entire case 

 is of brass. 



To prepare the case for use, a Negretti and Zambra deep-sea ther- 

 mometer is passed into the long tube, where it is held in place by means 

 of two rubber bushings. The sounding wire is fastened into the lower 

 clamp and passed through the open space between the slip hooks, which 

 are then allowed to come together at the ends. A messenger has been 



