﻿G2 Effect of Discharge of Lightning upon an Oak- Tree* 



Objection II. " If the new method leads, or appears to 

 lead, to any physical results not attainable by the ordinary 

 method, that can only be because along with the new method, 

 we have introduced some new hypothesis unawares." 



Answer. In point of fact the physical result is attainable by 

 the ordinary method. For " p " let Mr. Burbury read " total 

 number of systems for which the variables x a , y a , z a , #«, . . • • «'» 

 lie between the limits x a and a'a + dtca, y a and y a + dy a , z a and 

 Za + dza, Mb and tf'j + dse h , . i . . it) n and w n + dw n , divided by 



dxT a dy a dz a dxb dw n " &c, and the result will have 



been attained, although perhaps without much elegance or 

 conciseness. 



But if the ultimate test of any " physical result " is to be 

 whether or not it is attainable by the "ordinary" method, 

 then let physicists be warned against new methods, and let 

 us admit that Nature herself must be " introducing a great 

 many hypotheses unawares." 



Princeton, N.J. 



VIII. Letter from Mr. Barber Starke y describing remarkable 

 results of a Discharge of Lightning upon an Oak- Tree ; 

 with Note by Lord Kelvin. 



Dear Lord Kelvin, June 4th, 1906. 



ABOUT 5 o'clock on the afternoon of August 29th last 

 year during a severe thunderstorm, three Oak-trees 

 were struck in the Park ; and in one case the effect on the 

 tree was so remarkable that I think I ought to describe it to 

 you. A large number of shreds of wood, probably not fewer 

 than two or three dozen, and varying from 1 to 3 feet in 

 length, and of an irregular breadth of T 'g to ^ of an inch, were 

 torn out of the bole of the tree, and remained with one end 

 fixed in the ground to a depth of 1 inch or more, standing in 

 a more or less nearly vertical position inclined towards the 

 tree, at a distance of about 15 feet from the bole of the tree 

 on the west side. These irregular shreds were so light and 

 flexible that the act of falling could not have placed them in 

 the position described. Apparently they had been sucked 

 into the ground. Could this have been caused by any elec- 

 trical action ? 



When I visited the tree a few days ago, I still found one of 

 these shreds embedded in the ground. 



I am, Yours very truly, 



W. I. S. Barber Starkey. 



