March, 1919] Temperatures of Ten Thousand Smokes 251 



that acquaintance with their behavior nor to test the accuracy 

 of their readings, which everyone will recognize as highly 

 desirable prehminaries to the use of any instruments. 



But notwithstanding these handicaps, the instruments did 

 good service in the field, giving identical and apparently 

 trustworthy readings at all times. At the beginning of the 

 work their readings were compared in the vapor of Fumarole 

 No. 1, which was convenient to our camp; and again at the 

 close of the season, when checked at the same vent, they gave 

 the same readings as at the beginning, thus allowing us to 

 repose confidence in their readings throughout. 



Two months later, when they were unpacked after being 

 returned to Columbus, it was observed that, while the Hoskins 

 instrument was apparently still in good order, the battery 

 (dry cell) of the pyrovolter had completely gone bad. They 

 were then repacked and shipped to the Geophysical Laboratory 

 where they were recalibrated by E. D. Williamson, who reported 

 as follows: 



"Temperature, 448, 444, 441, 433, 351, 348, 254. 



Reading (Hoskins Instrument), 458, 453, 450, 443, 359, 355, 259. 



Reading (Pyrovolter), 441, 442, 441, 438, 348, 343, 255. 



"The readings in the first row were taken with Pt. Rh. thermoele- 

 ment. You will notice that the Hoskins combination reads consistently 

 about 2% too high, while the other is less consistent, but does not 

 involve errors greater than the expected accuracy permits. We found 

 that the battery in the pyrovolter was completely used up, but hope 

 that this did not affect any of your readings. 



' ' The two thermometers were calibrated at the boiling point of water, 

 where each read 0.3° too low." 



Following this report the readings observed in the vents 

 have been corrected to accord with the recalibration. Because 

 of the great variations encountered from place to place in a 

 column of escaping gas it was not considered advisable to 

 attempt to read the instruments closer than the nearest 5°. 

 Where the correction is applied the resultant temperatures are 

 usually expressed by an intermediate figure. They are recorded 

 as they came out after correction, but such temperatures, as 

 for example 299° C, would be best considered as 300° C, for no 

 implication that the errors are less than 3° either way is intended. 



The method of procedure in the field was, starting out in 

 the morning with packs containing thermometers, one or both 

 pyrometers, 5x7 camera, Kodaks, spade and other necessary 



