136 



Mr. W. Crookes on 



[June 15_, 



This gives a maximum error in the value of A of 6'20 per cent. Hence 

 we adopt the equation (5) as the best representation of the observations, 

 and as the best application of the Law of Fatigue. 

 For /3 = 1-0, we find 



A = 47-5 

 53-3 

 52-4 



51- 



50- 

 47-0 



52- 7 



51- 8 



Mean .... 50-7 



We may now proceed to calculate the values of n from equation (5), 

 using the constants 



A = 50-7 

 /3 = 1-0; 



and thus we obtain 



Dr. Macalister. 



No. 



t. 



71 (obs.). 



n (calc). 



Diff. 



1. 



0-50 sec. 



19-0 



20-2 



-1-2 



2. 



0-66 „ 



246 



23-4 



+ 1-2 



s! 



1-00 „ 



26-2 



25-4 



+ 0-8 



4. 



1-50 „ 



23-6 



23-4 



-fO-2 



5. 



2 00 „ 



200 



20-2 



- 0-2 



6. 



3-00 „ 



14-2 



15-2 



- 1-0 



7. 



4-00 „ 



12-4 



11-9 



+ 0-5 



8. 



6-00 „ 



8-5 



8-3 



+ 0-2 



This Table shows a very satisfactory agreement of the observations 

 wdth the Law of Fatigue expressed by equation (5) ; and this agreement 

 is also shown in the Diagram on p. 132, where the curve (5) is drawn 

 to scale, and where the individual observations are marked by the small 

 circles. 



X. On Hepulsion resulting from Radiation. Influence of the 

 Residual Gas.^^ — (Preliminary Notice.) By William Crookes, 

 F.R.S. &c. Received June 13, 1876. 



I have recently been engaged in experiments which are likely to 

 throw much light on some obscure points in the theory of the repulsion 

 resulting from radiation. In these I have been materially assisted by 

 Professor Stokes, both in original suggestions and in the mathematical 



