CASELLA-MILLER DEEP-SEA THERMOMETER. 



889 



a spatula, the water was kept thoroughly stirred up. When we had 

 steadied the temperature, the Casella was takeu from its bath of sea- 

 water, pluuged quickly in, and read at the end of every twenty seconds, 

 and at the same time the standard, which was so delicate that a breath 

 would affect it, was noted. 



Tests Nos. 1 and 3, in water and air, were for the purpose of compar- 

 ing all the thermometers. 



In Nos. 1 and 2 from want of practice, we did not succeed in main- 

 taining a uniform temperature throughout, but, as the effect of the grad- 

 ual cooling of the water was probably analogous to that experienced in 

 lowering the instrument to a great depth, through a constantly lowering 

 temperature, they may possess a value peculiar to themselves, and are 

 therefore given. As they were taken by the first method, they are not 

 strictly accurate, as the ice frequently prevented recording at the 

 instant, and as large pieces were stirred sometimes nearer and some- 

 times farther from the bulbs, the bath itself was irregular. 



This was particularly manifest when, at the end of ten minutes, more 

 ice was added, and the temperature suddenly lowered over 5'^ ; the 

 sensitive instruments marked it at once, the Casellas more slowly, but 

 attheend of five minutes had experienced a great fall. The inaccuracies 

 in reading are probably in no case over one degree. 



Test No. l.—Bath 53°, lotcering to 36° 5'.' 



The thermometers having been hung side by side in the open air and 

 shade for one hour and recording as per column were placed in bath. 



In the above table, as in all others, the correct temperature as shown 

 by No. 1 and the point at which each instrument came to it are printed 

 in Egyptian type. To the record of each instrument is applied its index 

 error, in estimating this point, viz : 1S.Q. 6, 2o.5 added, and from No. 8, 

 \^ subtracted, and the point within .5 of correct assumed to be so. 



Test ¥o. 2.— Bath 40^, lowering to 33^.5. 



The standard and three Casellas having been exposed in open air 

 and shade one hour, and recording as per column, were placed in bath. 



