284 Prof. J. A. Ewing and Mr. W. Low on the 



Table V. — Effects of various Loads in reducing the apparent 

 Air-space between True-plane surfaces. 



Load, 

 kilogs. per 

 sq. centim. 



Induction, 33, given in each 



case by a magnetic force § 



of 5 C.G.S. units. 



Thickness of 

 equivalent 

 air-space, in 

 millimetres. 



Before 

 cutting. 



After 

 cutting. 





 565 

 113 

 169-5 



226 



5600 

 5400 

 4700 

 4050 

 3650 



4700 

 4670 

 4200 

 3800 

 3650 



0022 

 0020 

 0-017 

 0010 



nil. 



add to the resistance of the joint. The following table 

 shows the induction reached under this load in the two cases, 

 and the thickness of air-space which would be equivalent to 

 the extra resistance which the gold-leaf apparently caused : — 



Table VI. — Effect of a Film of Gold-leaf between the Faces 

 at the Joint: Bar loaded with 226 kilogs. per square 

 centimetre. 



Magnetizing 

 force, §. 



Induction, 33. 



Thickness of 

 air equivalent 

 to the differ- 

 ence, in 

 millimetres. 



Without 

 gold-leaf. 



With gold- 

 leaf. 



10 

 20 

 30 



8170 

 13010 

 14830 



7920 

 12800 

 14720 



00049 

 0-0032 

 00018 



The influence of the gold-leaf is therefore small, when 

 compared with the quantities stated in the earlier tables. 



The results of the experiments, taken as a whole, are very 

 fairly consistent, but it must be admitted that they are not 

 readily intelligible. It is not difficult to suppose that an 

 actual film of air of such a thickness as would be re- 

 quired to explain the resistance of the joint may be present 

 between the greater part of the surfaces when the surfaces are 



