Referee report by G. C. Foster on 'The Mechanism of the Electric Arc' by H. M. Ayrton

                                <u>CONFIDENTIAL.
<\u> 

REFEREE'S REPORT. 

To the Sectional Committee for Physics & Chemistry 
Paper by Mrs H. Ayrton 
On "The Mechanism of the Electric Arc." 
1. Whether the paper should or should not be published in the "Philosophical 
Transactions? On the whole, yes. 
2. Whether, in the former case, it should be published in full or in part only, the part 
so to be published being indicated: 
The style is diffuse and I am convinced that the 
substantial facts might be stated, perhaps more 
clearly in appreciably shorter compass, but I cannot 
indicate parts that could be omitted from the paper 
as it stands. 
3. Whether any modifications are necessary or desirable, and, if so, of what nature: 
4. Which illustrations (if any) accompanying the paper should be reproduced
As the paper stands, the figures seem all to be required, though 
I hardly think all of them are intrinsecally necessary. (E.g., if the 
paper were recast, perhaps Fig. 11 might be dispensed with, and it 
might not be needful to retain all of 14, 15, 16) 
General Remarks. 
In one or two places the reasoning seems to me faulty or at least doubtful. 
E.g., page 8: - "The temperature of the film" [of supposed carbon vapour] "cannot 
rise, because there is no increase of pressure,<s>"<\s> ....". This implies that the volatilisation 
of carbon in the arc takes place at a fixed temp<sup>e<\sup> depending on atmospheric pressure, 
like the boiling point of a liquid. But there is no fixed temp<sup>e<\sup> of evaporation or 
volatilisation: the process only goes on quicker the higher the temp<sup>e<\sup>. On page 10 also 
volatilisation of carbon is spoken of as taking place at a fixed temp<sup>e<\sup>. - Page 12: 
"the quantity of carbon evaporated per second would be proportional to the 
area <u>a<\u> and also to the heat employed in evaporating it." If the doctrine