±20 Prof. Moseley in Answer to Mr. Earnshaw's Remarks 



has said that it was universal ? That Dodona of Epirus was 

 meant (the only real Dodona, indeed,) is evident from the 

 mention of the Graici, who were an Epirotic tribe. 



[To be continued.] 



LXVII. Professor Moseley in Answer to Mr. Earnshaw's 

 Remarks on the Principle of ' Least Pressure published in the 

 Philosophical Magazine for April. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 

 'T'HE objections originally alleged by Mr.Earnshaw against 

 -*■ the principle of least pressure were three in number. 



The frst had reference to a general principle on which the 

 demonstration of that principle was founded. 



The second referred, not to the demonstration of the prin- 

 ciple, but to an assumption made in the application of it, that 

 the value of each of a system of resistances was necessarily a 

 function of the coordinates of its point of application ; and 



The third applied itself to the particular case of three re- 

 sistances in the same straight line. 



With regard to his objections on these last two points, I am 

 disposed to doubt whether Mr. Earnshaw can be serious in 

 persisting in them ; and that I have good grounds for scepticism 

 on this point will, I am sure, be admitted by any person who 

 has taken the trouble to follow out the controversy between 

 us. That he should adhere to his first, and, as he calls it, his 

 principal objection, I can now fully understand. 



He has all along been labouring under a misconception of 

 one of the very first principles of my theory. It is only from 

 his last paper of objections, &c, that I make this discovery. 



He imagines me, it seems, to have assumed the directions 

 of the resistances of the system B to be given. 



Whence he can have collected this erroneous view of the 

 matter I know not. In the Number of the Phil. Mag. and 

 Journal for October 1833, in which 1 first brought the sub- 

 ject forward, and to which Mr. Earnshaw has frequently re- 

 ferred, he will find a summary of the analytical operations, by 

 which the amount and directions of each resistance may be 

 determined in terms of the coordinates of its point of applica- 

 tion. It is therefore very evident, and might have appeared 

 to Mr. Earnshaw, that I had considered the direction of each 

 resistance to be a function of those coordinates, and not 

 otherwise given than in terms of them. But he concludes 

 that I have put the consideration of the directions of the forces 



