influenced by the Earth's Motion 



219 



readings made in the neighbourhood o£ noon on June 19. 

 Five readings were taken in each position and then the board 

 was reversed. The headings "East" and "West" indicate 

 the end at which the observer was sitting ; " East " therefore 

 meaning that the course of the light was from West to East. 



Table I. 



Time ll h 30 m . 



Timell h 50 m . 



Time 12 h 5 m . 



Time 12 h 15 m . 



Time 12 h 25 m . 



Temp. 17°-4. 



East. 



Temp. 17°-7. 

 West, 



Temp. 17°-9. 

 East. 



Temp. 17°'9. 



West. 



Temp. 17°-9. 

 East. 



o 



457 



o 

 45-4 



456 



45-9 



46-0 



45*5 



459 



45-8 



45-7 



461 



455 



454 



45-5 



45-9 



46-1 



45-6 



45*7 



45-6 



45-7 



46-0 



456 



457 



45-7 



45-8 



46-0 



45-58 



45-62 



45-64 



45-80 



4604 



1 



The mean of the three " Easts " is 45*75, and of the two 

 "Wests" is 45*71; so that 



E-W=+-04°. 



All these numbers are in decimals of a degree. The pro- 

 gressive alteration in the readings corresponds to the rise of 

 temperature. It would appear that, as was natural, the 

 quartzes lagged somewhat behind the thermometer. 



Table II. — Noon. 



Date. 



! 



E-W. 



June 17 



+•03 



-•05 

 +•04 



„ 18 



„ 19 



Mean 



+•007 





Three sets of observations were taken at noon, and the 

 results are recorded in Table II. In two other sets taken 



