MISUNDERSTANDINGS 139 



the Professorship of Natural Philosophy in the University of Edinburgh, in the event 

 of that office becoming vacant, I consider it to be only just to Mr Tait to attest 

 that, in consequence of a rather copious correspondence between him and me, which 

 has been carried on for somewhat more than a year, on mathematical and physical 

 subjects, including Quaternions, and the Wave-surface of Fresnel, my opinion of the 

 energy and other capabilities of Professor Tait for any such appointment is very 

 favourable indeed. 



WILLIAM ROWAN HAMILTON. 

 OBSERVATORY OF TRINITY COLLEGE, 

 DUBLIN, Dec. loth, 1859. 



Tail's return to Edinburgh and his assumption of new duties meant 

 a considerable break in the line of his mental activities ; and it was not 

 till Dec. 4, 1860, that he wrote letter 44 of the quaternion series to 

 Hamilton. A few days earlier he had sent Hamilton a copy of his inaugural 

 address, in which he had referred in glowing terms to the " powers " of 

 Hamilton's " tremendous engine," to the great secret of quaternion applications, 

 which "seems to be the utter absence of artifice, and the perfect simplicity 

 and naturalness of the original conceptions." 



EDINBURGH, 



Dec. 4tA, 1860. 

 My dear Sir William Hamilton, 



I received your letter this morning and am glad you are pleased with 

 my introductory lecture. Its treatment by others has not been in all cases so lenient, 

 in fact I am now doing battle with at least two opponents, who have vigorously 

 attacked different parts of it. I am sure I am not violating confidence in telling 

 you that one of these attacks is directed against the mention of Quaternions (towards 

 the end of the lecture) as "likely to aid us to a degree yet unsuspected in the 

 interrogation of Nature." The writer, I daresay, is a personal friend of your own 

 that I do not know but, at all events while speaking of you with admiration and 

 due courtesy, he protests in the interests of Science against my having published 

 such a sentence as that above quoted... 



I was sorry to see from your letter that we must have been completely 

 misunderstanding each other for some time as to my projected publication on 

 Quaternions. In the first place, to prevent all misconception, let me say that when 

 Dr Andrews wrote a note introducing me to you as a correspondent, I had not the 

 slightest idea of ever being the author of a Volume on the subject. So he could 

 know nothing whatever about the matter. And I think you will acknowledge that 

 the whole is a mistake when I tell you that it never entered into my head to write 

 a Book on Quaternions till I was asked by some Cambridge friends to do so, that 

 I at once wrote to you about it, and asked how far it might be consistent with 

 your wishes or plans that I should undertake such a work. In my letter to you, 

 No. 38, I proposed two forms of publication, one a dry practical treatise, very short, 

 assuming most of the fundamental laws of Quaternion multiplication, but stuffed 



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