To Thomas Archer Hirst   Sunday Aug. 4th 1850

Manchester Sunday Aug. 4^th 1850

My dear Tom

Well the ordeal is over and here I am again. I started to Edinburgh on Wednesday morning last and reached there the same night, taking up my quarters in a temperance hotel, being converted thereto by one of my fellow travellers. On Thursday morning I enrolled myself as ‘an associate’ by paying a pound and finding that Saturday was intended for excursions I knew that if I could not get my paper read on Friday I should have to wait till the next week. I saw the Secretaries of the Mathematical and Physical Sections¹ and expressed my wish to have the opportunity of reading the paper next day. One of them, the professor of natural philosophy in the University of Glasgow² spoke of the great interest the subject excited, but could not bring himself to accept my explanation in toto. For the most part he agreed with me fully but on certain points of importance he felt compelled to dissent; – He strongly wished us to have a conversation together before the paper was read, but this except for a few minutes next morning was not attained. These few minutes however were invaluable to me, as I had time to turn his objections over in my mind instead of having to combat them impromptu. Well on Friday morning the name of your friend³ appeared upon the public list in the respectable society of Sir David Brewster and others. I sat among the audience, a paper was read by some gentleman upon meteorology and then the President announced that the next paper was by M^r Tyndall on the Magneto Optic Properties of Crystals.⁴ I arose fumbled towards the rostrum where I soon found myself with lord [Rochly]⁵ to my immediate left, next him Sir David Brewster, next him professor Forbes the president of the Section and other members of the committee, on my right were two professors of my own age perhaps,⁶ the one he whom I have already mentioned the other a Cambridge fellow. Well I felt either the God or the devil, or perhaps the abstract strength belonging to each very full in me at the moment, I was never more at home in my life and from beginning to end felt no trace of alarm or hesitation. I had looked at the case before-hand and determined not to be cowed. The paper was listened to with great attention and just before me were a bunch of ladies with mild brown eyes and every time I raised mine I found theirs fixed on me as if I had been reading the story of Jack and the beanstalk or something else equally interesting – It must have been the half dare-devil way in which I spoke and not the subject itself that interested them. Well at the conclusion the president⁷ arose, passed a high eulogium on the paper, said however that he had been in Bonn himself very lately, had seen Plücker and seen his experiments which appeared in the highest degree conclusive and satisfactory, said moreover that he knew how impossible it was to form a correct conclusion as to the theory from seeing merely a few experiments. I arose and said that I had experimented for 10 hours a day during the space of three weeks under the conviction that Prof. Plücker’s theory was fully established. The president then invited any gentleman present to make any remarks which he thought called for upon the paper just read, and if any part appeared objectionable to him to state his objections. The Glasgow professor to my right arose, and commenced by introducing Poissons theory of magnetism, and said that he had not the shadow of doubt that the paper would corroborate the theory fully and that the theory would support the views advanced in the paper. He was profuse in his praises of the beauty and ingenuity of the experiments; but one thing appeared to him to be not at all established and that was that the action of the dough was due to the proximity of the particles and not to the optical axis, ‘for’ said he ‘the powder of which the dough is composed is a crystalline powder and the pressure exerted upon this is exactly what might be expected to cause the little component crystals to take up a position in which their optic axes would come into play. Indeed he exclaimed rather triumphantly this very specimen of bismuth dough is the strongest proof of what I say. Look at it you see the particles are all minute plates or scales and these being pressed flat cause the action.

He then went on to contend that Faradays view of a directive force was the correct one – it may said he differ from the views of M^r Tyndall in some minor particulars but they are substantially the same.

I have proved he continued and I intend to lay the matter before the Section at a future day, that crystals have three lines of equilibrium, at right angles to each other and no matter how the crystal is hung one of these lines will stand from pole. I have worked out the formula for the magnetic and diamagnetic forces under the circumstances. He concluded by repeating the eulogium which had at commencing passed upon the paper.

Of course I cannot repeat the 10^th part of what he said nor the arguments he adduced in support if his views.

I arose again but the president anticipated me and asked whether any other gentlemen had a remark to make. one present proposed a question or two to my antagonist and there being no other questioner present I was called upon to defend myself.

At this time people kept thronging into the room. the president had to rise several times and request them to ascend to the upper seats and not to block up the passages Well I got up again and said that with regard to M^r Faraday (my antagonist appeared anxious to stand up for him) I had only to express my unqualified admiration of his experiments. he had described not only every action but every shade of action with perfect exactitude, I had had the pleasure of seeing M^r Faraday a few weeks before and then told him that we had been compelled to dissent from his views, ‘no matter’ he replied ‘you don’t differ from me as a partisan but because your convictions lead you to differ from me’ – ‘thus encouraged by M^r Faraday himself,’ I proceeded ‘I feel rather inclined to stick to my old notion in this matter notwithstanding what has been urged by Professor Thomson – Prof Thomson has remarked on the necessity of care and caution in coming at the bare facts in a case like the present; I fully agree with him, and I could tire the audience with a recital of the experiments made to obtain these facts. We have examined nearly 100 natural crystals and in some cases from 10 to 20 different specimens of each. while a vast number of artificial crystals have also passed through our hands. So much for care. Prof. Thomson has stated a hypothesis of his own that magnetic action in crystals can be reduced to three lines of equilibrium and that there are only three. unfortunately for him the hypothesis is against facts. Take a disk from Calcareous Spar cut perpendicular to the Optic axes, such a disk suspended horizontally has three lines of equilibrium thus suspended; the optic axis is another line of equilibrium, here we have four instead of three as affirmed by Prof. Thomson.’ ‘Have you made that experiment M^r Tyndall?’ asked he ‘yes’ said I ‘repeatedly’ [‘]has your disk been perfectly circular?’ ‘perfectly circular’ I replied ‘and your crystal pure?’ said he ‘that also’ I responded ‘well I can only say’ said he ‘that it is most extraordinary and entirely contradicts my notions on the matter’ ‘Prof. Thomson’ I continued has raised an objection against my experiments with the magnetic and diamagnetic dough supposing that the arrangement of the minute crystals and not their proximity caused the action – ‘Now’ said I ‘it is a well known fact that if a precipitate of carbonate of lime be washed out with boiling water[’] (here Thomson interrupted me – ‘dont you think M^r Tyndall that if the precipitate was examined by a microscope it would be found to be composed of small crystals?’) ‘I’m just coming to your question’ I replied – The washing with boiling water induces sometimes a crystalline structure, but when these crystals are examined under the microscope as Prof. Thomson suggests they are found to be of the form of arragonite⁸ not of calcareous spar (which I ought to have remarked was the case under consideration) now it is utterly incredible that a jumble of small arragonite crystals could exhibit exactly the deportment of calcareous spar; but more than that’ I continued ‘the precipitate has been washed with cold water and has no crystalline structure whatever, this mass’ said I ‘holding up a model made of your carbonate between my finger and thumb – this model is a perfectly amorphous mass, there are no crystals there[’] said I ‘squeezing the thing to a fine white powder and scattering it over the table. and even in the case of this bismuth dough if you look at it transversely you will see as many plates as you see upon its surface’. I broke the disk and handed it to Prof. Thomson – he shook his head as if but half convinced – Sir David Brewster arose and said it appears to me that the supposition of Professor Thomson is exceedingly improbable, but it can be decided at once – does the mass cleave?’ – ‘no Sir David’ I responded, ‘not at all, it is a purely amorphous mass[’]. The old fellow evidently thought as I thought. Thomson got up again and said that the bismuth was not at all convincing but that the carbonate of lime according to the facts stated met his objection fully. He said to me at the end that I should find his opinion and the theory of Poisson in entire harmony with my views. This is only a bare outline of the discussion Tom, I wish you had been there. I was never more at home in my life. I enjoyed full freedom of thought and utterance and the whole matter was to me the keenest amusement – The vote of thanks was right warmly responded to, and an old gentleman a member of the committee said to me when done – go in to the committee room M^r Tyndall and make me an abstract of your paper. I want to send it off to the Athenaeum⁹ – In passing thru’ the street towards home, another gentleman met me. ‘Oh M^r Tyndall’ he exclaimed – I looked at him I had never seen him before – ‘I have just heard your paper – I have taken notes but dont think I can represent the case fairly, would you oblige me with an abstract putting your argument in what appears to you to be the strongest light. I want it for the Literary Gazette¹⁰ – But the old door keeper which I encountered on leaving the Section was most characteristic of all – ‘Well Sir’ said he as I passed him ‘you have got your matter done’ yes I said. ‘Well Well’ he said chuckling ‘it was most interestin, I have na heerd any thing like it – Ah but you made out a strong case – Why Professor Thomson could make nothing of you’

Thus the affair passed Tom. I had a clear stage and an impartial hearing and had you been there I think you would have admitted that I did as much as could be expected from a poor devil like me.

To stop longer in Edinburg would have been against the interest of my exchequer. tho’ to remain would have been a pleasure and a benefit to me. yesterday excursions were made. and certainly the country around Edinburgh affords glorious opportunity for such. The evening meetings were also most interesting – but the stern fact was before me and I reconciled myself to it half lovingly. took my portmanteau cheerily in my hand and bade Edinburg good bye yesterday morning. this is the reason I have not written to you from Edinburg, because I have arrived here as soon as a letter could have done -

With best love my dear fellow – | Your affectionate Tyndall

Kiss Jimmy for me! if he lets you –

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