PAPERS OX CHEMISTRY AND PHYSICS 341 



Five complete twists were given each end of the quartz 

 thread in order to hold the weight-lever horizontal and 

 the observing lever perpendicnlar. 



. The apparatus was enclosed in a T-shaped tnbe of 

 brass and was evacuated to 0.03 mm. mercniy pressure, 

 and dried with phosphorous pentoxide. The apparatus 

 was placed in the basement on a solid base; however, 

 passing trucks gave a very noticeable vibration. The 

 temperature of this room was constant to within one de- 

 gree in 24 hours. A galvanometer telescope-scale was 

 used for observing deflections. Distance was 60 cm. The 

 following readings and curve are t^'jjical of many taken. 



Date Time Scale Room Temp. Remarks 



Nov. 7 7.30 AM 23.2 19.0°C 



8.45 AM 26.7 1S.5 



12.00 Xoon, 22.0 19.0 



2.30 PM ' 19.2 19.2 



5.30 PM 17.4 19.4 



6.00 PM 16.6 19.5 IMoon at zenith 6.12 



6.14 PM 15.9 19.5 

 6.20 PM 15.8 19.3 

 S.OO PM 16.1 19.8 



8.15 PM 16.5 19.8 

 Nov. 8 6.30 AM 22.7 19.3 



8.00 AM 23.5 19.2 



The evidence of this experiment shows that if the 

 earth's gravitational force is balanced against the torque 

 in a quartz liber, the moon will disturb that balance 

 gradually over 24 hour periods. A maximum decrease of 

 the earth's gravitation occurs with the moon at its upper 

 culmination and a minimum at the moon 's lower culmina- 

 tion. 



The author expects in the liear future to try to detect 

 any lag effect in the gravitation of the moon and the sun. 

 Of course many changes will be necessar)' to adapt the 

 apparatus to such measurements. 



The facilities of the Laboratory of Physics of the Uni- 

 versity of Illinois through the courtesy of Professor A, 

 P. Carman were placed at my disposal for this investi- 

 gation, while the council and help of Dr. C. T. Knipp were 

 a large factor in its success. 

 Laboratory of Physics 



L'niversitv of Illinois 

 Septem'ber, 1921 



