[731 U. S. FISH COMMISSION STEAMER ALBATROSS. 75 



The entire apparatus is made of brass except the Sigsbee clamp, 

 ^hich is of phosphor brouze, and the rubber liniugs of the thimbles g. 



To mount the thermometer unscrew the cap i, drop a spring h into 

 the case, slip a thimble g over the glass shield at ff, put the thermom- 

 eter in the case, droj) in another thimble, which will rest on the ui)j)er 

 end of the shield, then place another spring on the thimble and screw 

 the cap in place. The thermometer will then be suspended between 

 delicate spiral springs at the ends and soft rubber rings which sur- 

 round the shield. This arrangement has proved effectual in guarding 

 the tliermometer against jars incident to the service required of it on 

 board of the Albatross. 



To take a. temperature set the spindle o into the hole in the cap i by 

 screwing it down until the propeller blades strike the set screw ^j; then 

 by means of the Sigsbee clamp q secure it to the temperature rope. 

 The bulb v/ill then be down and the mercury in the tube connected with 

 it, the ]iositi()n required to take the temperature. The water acting on 

 the propeller during the descent will keep it in position resting against 

 the set screw j>, but as soon as the reeling in begins the propeller is set 

 in motion, bringing the screw on the upper end of the spindle into 

 action, gradually raising the propeller until the lower end of the spin- 

 dle is withdrawn from the hole in the cap ^, when the thermometer 

 promjitly turns over and registers the temj)erature by breaking the 

 column of mercury at the point a, the column then falling to the bot- 

 tom of the tube. 



It can be read at any time afterward, as changes of temperature do 

 not affect the reading after the column is once broken. 



The apparatus described above is simple and reliable. 



THERMOMETERS FOR AIR AND SURFACE TEMPERATURES. 



These thermometers are made by J. & H. J. Green, New York. The 

 tubes are 10 inches in length, extra strong, and the scales are distinctly 

 marked on them. Two-tenths of a degree is the greatest error found in 

 testing them. 



THE MILLER-CASELLA DEEP-SEA THERMOMETER. 



Plate XL shows this thermometer in the copper case used for deep-sea 

 work; also partially dismounted to show the form of construction. The 

 magnet seen between the two instruments is used to adjust the Indices. 



The following description is from Sigsbee's Deej)-sea Sounding and 

 Dredging: 



"A glass tube bent in the form of U is fastened to the vulcanite frame, 

 and to the latter are secured white glass plates containing the graduated 

 scales. Each limb of the tube terminates in a bulb. A column of mer- 

 cury occupies the bend and a part of the capillary tube of each limb. 



The largei bulb and its corresponding limb above the mercury are 



