MR. A. E. TTTTTON ON A COMPENSATED INTERFERENCE D1LATOMETER. 359 



Correction, 0'04, 0'06. 



Corrected number of bands, / 2 ' = 32-16, / 3 ' = 60'16. 



Wave-length of light employed, X = 0*0006562. |X = 0'0003281. 



Diminution of thickness of air-layer, / 2 ' X = O'Ol 05520. /,' $ X = 0'019739. 



Elongation of tripod screws, 



I 



I 



10- 9 (8600 + 4-56 - l - 



10- 9 8600 -f 4-56 ' 



(t. z ,) = 0-0067481. 

 (t, ti) = 0-012417. 



\ 2 



Expansion of aluminium block, 



Lt 2 L, = 0-010552 + 0-0067481 = 0'0173001. 



U 3 Lt L = 0-019739 + 0-012417 = 0-0321 56. 

 0=0-00026894. <=0-OOOC0012937. 

 L = 12-1858. 

 a = 0-000 022 070. b = O'OOO 000 010 617. 



SERIES 3. 



Thickness of aluminium block, Li, = 12"188. 

 Length of screws above table points, I = 12'812. 

 Thickness of air-layer, d = 0'624. 

 Temperatures, , = 9'8, t z 67'6, t 3 = 1187. 



t z ti= 57-8. t 3 ti = 108-9, 

 Pressures, b t = 772'6, 6 2 = 771 '7, b 3 ~ 771 '9 millims. 

 Number of transited bands, / 2 = 29'43, f 3 = 57'] 8. 

 Correction, O'll, 0'18. 



Corrected number of bands, / 2 ' = 29'32, / 3 ' = 57'00. 

 Wave-length of light employed, X = 0-0006562. J X = 0'0003281. 

 Diminution of thickness of air-layer, // 1 X = 0'0096199. f 3 % X = O'Ol 8702. 

 Elongation of tripod screws, 



4-56 ' 



( 2 ,) = 0-0064992. 

 (, ^) = 0-012407. 



\~ 2 



Expansion of aluminium block, 



L 2 L^ = 0-0096199 + 0'0064992 = 0-0161191. 



Lt 3 Lti = 0-018702 + 0-012407 = 0'031109. 

 0=0-00026858. < = O'OOO 000 132 75. 

 LO= 12-1854. 

 a = O'OOO 022 041. b = O'OOO 000 010 895. 



