Determining the Elastic Constants of Glass. 



.61 



Table II. Glass 2. 



Width of beam = 4-45 cm. Thickness = "452 om. 



Bending moment = 35*7 kg. cm. 

 The values given in the first column show a mean transverse 

 curvature greater over the outer fringes than over, the inner ones 

 after one minute, while after 50 minutes this difference has 

 entirely disappeared (col. 3). The values in columns 2 and 

 4 are in this case not very significant as their variations in 

 most cases do not lie outside the limits of error of measurement. 

 The longitudinal curvature shows a slight increase. In this case 

 the increase, though small, seems to be significant as it is persistent. 



Table II.— Glass 2. 

 Transverse Fringes. 



N. 



After 1 Minute. 



After 50 Minutes. 



A 2 __ A 2 

 -A-n + lO A « 



^(A n . f2 2 -A^). 



T MA, i+10 2 -A, ( 2). 



KK+2 2 -K 2 )- 



10 



1 

 2 



3 

 4 



5 ~ 

 6 

 7 

 8 



9~~ 

 10 



•413 

 •410 

 •412 

 •412 

 •405 

 •409 

 •411 

 •407 

 •406 

 •403 



" j. -393 



•403 

 •403 

 •404 

 •405 

 •405 

 •403 

 •404 

 •405 





■ -399 



;•■} -405 



" [ -399 



" [ -409 



•404 

 404 



y -412 



11 

 12 



Mean Value 





Mean Value 



13-16 



17-20 



■409 



•393 

 •412 



■404 



•398 

 •401 



Longit 



udinal Fringes. 



\ 



N. 



i('A w+4 2 -A M 2 ). 



6"(A« + 6 2 _ A n 2 ). 



1 

 2 



3 

 4 



•108 



•no 

 •no 

 •no 



•108 

 •109 

 109 

 109 

 .110 

 •110 



5 

 6 



Mean Value 





33 



Mean Value 

 ■1092 



