[m'lkod a BARNES] ON THE DIFFERENCE IN TEMPERATURE 73 



Month 



1903 



July 



August 



September 



October 



November 



December 



1904 



January 



February 



March 



April 



May 



8- 17 



7-23 



24-78 



39-27 



59-72 



11-55 



8-12 



• 5-89 



6 79 



3-73 



j^o attempt has been made to trace the connection between wind 

 or general weather conditions and the differential curves. Without 

 consideration of such effects it would appear that the following re- 

 lations hold: 



a. Normal differences in temperature vary with the average air 

 temperature increasing negatively as temperature falls. 



h. Departure from normal differences in a negative direction in- 

 dicates lawer air temperatures and in a positive direction change to 

 warm weather. • . 



Besistance Tests on ilie Eecorder and Line. 



At the outset, before we undertook the series of measurements of 

 the difference of temperature between the mountain and the observat- 

 ory, we satisfied ourselves on many points in connection with the ac- 

 curacy of the recorder and leads. 



Our first tests were made on the insulation of the line. The leak- 

 age between the different wires leading up to the mountain and be- 

 tween these wires and the earth, during a period of prolonged wet 

 weather, was obtained when any fault in the insulation would have 

 been at once apparent. These tests were carried out with a batter>^ 

 and a hi^h resistance electric fester. Tthe deflection was obtained 



