472 



HYDROGRAPHIC MANUAL 



Page 404 



mometer is enclosed and sheathed in strong glass with the mercury reservoir of the ther- 

 mometer projecting into a cylinder containing the water sample and the graduated 

 stem extending upward into a tube at the top of the container, where it may be read. 

 The insulated water bottle can be used only to a depth of about 300 fathoms and tem- 

 peratures obtained in this way must be corrected for a small decrease in temperature 

 caused by the decompression of the water sample and bottle. Its advantage lies in 

 the fact that the temperature and water sample are obtained simultaneously with one 

 instrument. 



472. Reversing Thermometer Frames 



A necessary adjunct to a deep-sea reversing thennometer is a frame which protects 

 the thermometer, and by which it may be capsized at any desired depth by means of 



A 



C 



TiGUKE 86.— Oceanographic instruments in position to sound. A. Improved Sigsbee watercup. B. Tanner-Sigsbee reversing frame 

 and reversing thermometer. C. Sounding lead with snapper type of sampling device attached. D. Belknap-Sigsbee specimen 

 cylinder with sounding weight attached. 



certain mechanical attachments. Some frames are capsized by a messenger which trips 

 the inverting mechanism, and others utilize a propeller which revolves as the instrument 

 is drawn upward through the water, withdrawing a pin that allows the thermometer to 

 capsize. Some reversing frames are incorporated in instruments used to obtain water 

 samples (see 474), but the frame generally used by the Coast and Geodetic Survey is 

 designed exclusively for inverting the deep-sea thermometer. It is known as the Tanner- 

 Sigsbee reversing frame. 



