308 Mr. A. E. Tutton, 



Calculated Expansions. 





Diminution of thickness 



Expansion 



of tripod 



Expansion of nickel 





of air- 



layer. 



screAvs. 



block. 







For t, - t x . 



For t s - t Y . 



u. z - u v 



L* 3 — L# t . 





'0*0020933 



-0045639 



0-0046086 



0-0095348 



-0067019 



-0140987 





21064 



45869 



46240 j 



95572 



67304 



141441 





21163 



45213 



46433 ' 



94602 



67596 



139815 





23591 



49248 



51185 ! 



101953 



74776 



151201 





23623 



49707 



52006 i 



103355 



75629 



153062 





23328 



48986 



50927 ! 



101993 



74255 



150979 





18210 



37863 



38958 ! 



76927 



57168 



114790 





17750 



37338 



38229 



76231 : 



55979 



113569 





17521 



36945 



37869 



75638 



55390 



112583 



Calculated Linear Coefficients of Expansion. 



e. $ ■ j 



0, 





a. 



b. 



f 0-000 121 54 



0-000 000 072 7 



9-7985 j 



-000 012 40 



0*000 000 007 4 



1 121 74 



72 6 



9-7986 i 



12 42 



74 



[ 121 91 



69 7 



9-7985 



12 44 



71 



f 129 45 



72 8 



10-2679 ! 



12 61 



71 



1 128 37 



79 9 



10 -2679 



12 50 



78 



L 129 26 



72 6 



10-2678 



12 59 



71 



f 097 74 



59 9 



7 -8327 



12 48 



76 



1 097 56 



60 6 



7 -8328 



12 46 



• 77 



L 097 43 



612 



7 -8328 



12 44 



78 



Mean values . . 



-000 012 48 



-000 000 007 4 



The mean coefficient of linear expansion, a + bt, of pure nickel, 

 between 0° and f , is thus found to be 



0-000 012 48 + 0-000 000 007 4/, or 10- s (1248 + 0-74/). 



The true coefficient, a, of linear expansion at f , or the mean coeffi- 

 cient between any two temperatures whose mean is /, is oc = a + 2M> 

 that is 



0-000 012 48 + 0-000 000 014 8/, or 10" s (1248 + 1-48/). 



The order of agreement of the nine individual determinations 

 must be regarded as highly satisfactory, and those for each series of 

 three referring to the same direction particularly so. The slight 

 differences in the value of a for the three directions, possibly due to 

 slight internal strain, fully justify the author in having carried out 



