84 abstracts: physics 



sky will be more accurate, 'On an average, than one in sunshine. Hence, 

 the ideal condition would be an afternoon with a moderate wind and a 

 cloudy sky. 



The line divides the long circuit between San Diego, California, and 

 Seattle, Washington, and completes another direct connection between 

 sea level on the Atlantic and Pacific coasts. H. G. Avers. 



PHYSICS. — Calibration tables for copper-constantan and platinum-plan- 

 tinrhodium thermo-elements. L. H. Adams. J. Am. Chem. Soc, 

 36: 65-72. 1914. 

 Thermo-elements, if they are to yield accurate readings of tempera- 

 ture, must frequently be recalibrated by determination of their electro- 

 motive force at a series of fixed points and subsequent interpolation. 

 The labor of interpolation is minimized by the aid of the tables presented 

 in this paper, which give temperatures and temperature differences for 

 each 100 microvolts up to the limit of usefulness of each thermo-ele- 

 ment, and are used in combination with the appropriate derivation curve 

 deduced for each element from the observations at the fixed points. 



L. H. A. 



PHYSICS. — T her mo-element installations, especially for calorimetry. 

 Walter P. White. J. Am. Chem. Soc, 36: 1856-1868. 1914. 

 Potentiometers for thermo-electric measurements, especially in calorim- 

 etry. Walter P. White. J. Am. Chem. Soc, 36: 1868-1885. 

 1914. 

 These two papers describe a type of auxiliary installation for thermo- 

 elements which in high-temperature measurement and other work of 

 moderate precision is valuable for its convenience, quickness, and com- 

 prehensiveness, and which is also capable of the very high precision 

 often desired for calorimetry. 



When a thermo-element is used with its two ends at nearly the same 

 temperature, a condition easily provided in calorimetry, the relative 

 precision required in the electrical measurement falls to a value no 

 greater than that desired in the temperature reading, and the most 

 serious errors ordinarily affecting the electrical thermometer practically 

 disappear. 



The absolute electrical precision required is also comparatively low. 

 With a convenient and easily made copper-constantan multiple thermo- 

 element of 24 couples, 0.0001°C. corresponds to 0.1 microvolt. 



The satisfactory attainment of a precision of 0.1 microvolt demands 



