1040 PROFESSOR TAIT ON THE 



Thus the differential of the whole y-momentum which comes to unit surface on x = 

 from the layer x, x + dx, is 



W^'fl-M ^ 11 ° Z S % ^n cos + BAin Odd . 

 4^ \ 2v cost? y\ -r ' j 



Integrating with respect to <f> from to 27r, to x from to oo , and to 6 from to ^, 

 and doubling the result, we have 



The first term expresses my former result, viz. 



BPCj 



Sirs 2 Jh ' 

 But the whole is 



BPn C ? 4 ve\ 2BP™ fvhv 3 2BPC. 



3 w /" 7 4 ve\ _ 2BPw /X> 3 _ 

 Uj^Ke e 2 )~ 15j ~^~loTrs 2 Jh 



The ratio is 2C 3 /5C l = 3-704/4-19 = 0-882. 

 It is worthy of remark that the term 



/ 



has the value 



15W7TS 2 ^A 



and that 4/5ths of the C x term are due to e'. 



D. Thermal Conductivity. 



Applying a process, such as that just given, to the expressions in § 39, we find that 

 the exponential in the integral for the number of particles must be written 



g 2» 2 = s ( 1— e cc 2 sec 0/2-?; + -^ — ) 



to the required degree of approximation. [Properly, the superior limit of the 9 integra- 

 tion should be cos -1 - ; but this introduces quantities of the order a 2 only.] Thus equation 

 (1) becomes 



In the same way equation (3) of § 41 becomes 



E= -j /nv&((£+fye-5alv-9al4ev) . 



