DEEP-SEA THERMOMETERS. 



639 



theruionieter stiri5cient to retain its original temperature till such time as 



the degree indicated by the thermometer scale could be read off, keeping 



at the same time the bulb of the 

 thermometer immersed in the 

 water, I prevailed on an ingenious 

 mechanic to attempt the structure 

 of such a case a? I wanted, in 

 which he most iappily suc- 

 ceeded." The person here alluded 

 to was Mr. Robert Jamieson, of 

 Glasgow, who was honoured with 

 the large silver medal of the 

 Society for the Encouragement 

 of Arts. 



Fig. 1, hereto annexed, repre- 

 sents a back view of the case, 

 ready for use, being a tube of 

 copper, which encloses a thermo- 

 meter ; Figure 2 represents a 

 thermometer, so enclosed. The 

 length of the whole tube, includ- 

 ing the lid, is about 18 inches, 

 and its external diameter 2 inches. 

 The lid, which has a check to fit 

 the tube, is about 2 inches deep, 

 and has a conical or puppet-valve 

 in it, which rises upward. At 

 the lower end of the tube is 

 another valve of the same descrip- 

 tion, which also rises upward. 

 These two valves permit the 

 water to pass freely through the 

 tube while it descends into the 

 P^9- 1. Fig. 3. water ; but so soon as it stops, 



the valves shut, and the water, 



admitted at the greatest depth to which the machine is sunk, remains in 



the tube, around the thermometer. 



1 is a back view of the case ready for use. In Fig. 2, a a represent a ring, or 

 collar, on which the thermometer-plate rests, to keep it clear of the lower valve; bb, the 

 upper valve and valve-tube cover ; c c, a bridge on which the neck rod, or journal, of 

 the valve works, through a hole in a swell in the centre of the bridge ; d d, lower part 

 of the journal, with a screw-head, which keeps it from rising through the hole in the 

 bridge ; e e, ends of the journals. 



In recording the Surface Temperature, care should be talsen that the 

 instrument is not affected by the hot water from the condenser, or other 

 causes. If the water be drawn up, time should be given for the receptacle 

 to acquire the same temperature as the sea, and the Thermometer must 

 be read immediately it is taken from the water. 



