From Thomas Archer Hirst   Augst 28th / 52

Marburg. Aug^st 29^th / 52

My dear John

I have now taken three days to think of the proposal in your letter,¹ and the advantages are so equally balanced that I have had the greatest difficulty in coming to a conclusion, it is one of those cases that require rather prompt decision for the more it is looked into and the more difficult it is; one thing that would have helped me much you did not state in your letter and that is, when, supposing you get the Professorship at Galway,² you will be required to enter upon your duties there – If I could have had one Semester in Berlin I should have been considerably more reconciled, for I am not alone concerned therein, I had made a promise to see young Dickinson settled there, to whom I could have been of some service and who is worth it – I hope however that at soonest you will not be required to leave Queenwood before November the later the better for me –

Well, the prompt decision I make is that if M^r Edmondson is willing I am also prepared to come to terms with him. I can make a year at Queenwood useful to me and I hope to him also but at the end of that time I must return to Berlin and Paris. That is the only consolation I have for giving up the plans I had set out for myself – And now about arrangements I am willing to undertake what you have done, 3 hours per day and lectures, and if required I should not hesitate to deal with the Farmers³ either; it is no pleasant task I know and I should therefore be willing enough to be excused, I leave that to M^r Edmondson As to the Salary, I am prepared to receive as much as I can get for I can use it though I shall not be obstinate about that matter, if I come I shall in any case throw my whole soul into the work and, between ourselves, considering the expense of my apprenticeship I think I might be worth £150 per annum to him. That however you will have most voice in deciding for you understand best my relation to pecuniary matters –

But now about my lodging that is the principle consideration with me. I must have a few square yards sacred to myself, it may be a weakness of mine but I am not inclined to forego it, your room there by no means suits me, it is not quiet enough, it has not the homeliness about it that my nature and custom demands, at proper times I am body and soul at M^r Edmondsons service but after that I claim my perfect freedom and independence. I must be out of the way of interruption and must not be overlooked. If this appears too much to demand in M^r E’s eyes, who has been brought up under the eye of boys, and finds his happiness therein, he must remember it is inexpressibly disagreeable to me who have been accustomed to very different habits. In short on this point I am strict, but on the other hand I am willing to make some sacrifices if necessary to attain it.

Do you remember our once visiting Queenwood and in the Evening we paid Yeats a visit in the adjoining house by the farm yard – I have that little room in my eye whenever I think of Queenwood and my request is that it or a similar one apart from the main building be given up to me should I come – As I said I shall not grudge a pecuniary sacrifice to attain it but I think it ought not to be demanded –

I am expecting every day to leave Marburg on a journey with my Brother,⁴ but I am anxious to hear again from you to know when in the event of success you will be leaving Queenwood Write therefore to me under cover to Herrn Pfarrer Schnackenberg, Braach bei Rotenburg Kurhessen. Dickinson will be there during the vacation and will know where to forward the letter to me – If by that time you have proposed me to M^r E. you can tell me how he takes it

<Handwritten letter ends; hereafter LT Transcript Only>

Since I last wrote⁵ I have repeated your experiments with Bismuth⁶ and corroborated every experiment. I succeeded after some trouble in getting a bar that set axial. I saw there that the Bismuth behaved exactly as a bar of a magnetic substance when in the latter the lines of greatest density were parallel; in the former however perpendicular to the length of the bar. This deportment you explained by shewing that the line of greatest density in the Bismuth strove to set itself in the weaker, and in the shale in the stronger quadrants of the Magnetic Field. You say however that a North pole in the Magnet induces a South pole in the Bismuth as in the shale. Now in the shale you consider the extremities of the line of greatest density as the poles, but in the Bismuth the lines perpendicular thereto. Now I am as yet not prepared to attempt any explanations but the thought struck me: Which must be considered as poles in a substance whose molecules are arranged symmetrically? In a bar of soft iron the molecules are homogeneous throughout and we take the ends as poles, the relation of the length to the breadth of the bar settles the question, but how when the molecules are differently arranged?

Then again, the repulsion of the whole mass of Bismuth by a magnet is after all somewhat difficult to reconcile with an induced polarity similar to a magnetic substance. If we send a current around a bar of soft iron we know what polarity is induced; if we replace the iron by a bar of bismuth with its particles arranged similarly (that is not crystallized) will it be similarly polarised to the Iron or not? Weber’s experiment I almost think is capable of answering this question, though for want of apparatus I have not done it at all satisfactorily yet.⁷ By means of a fine string attached to a wooden disc bearing a horse shoe magnet N R S, the latter is so suspended that it revolves in a horizontal plane and sets its poles N S in the magnetic meridian. This wooden disc bears a small plane Mirror whose plane is perpendicular to that of the magnet, faces R, and is parallel to the line joining the poles N S ab (Fig. 1) is the ground plan (c b) (Fig. 2) its elevation. A telescope T with a scale p q attached (as in magnetic observations) is placed at a little distance (6 feet) and the smallest movements of the Mirror noted. C P D is a copper tube of about an inch in diameter and two feet long. This is placed perfectly vertical to the plane of the Magnet and in the position shewn at P (Fig. 1) and projects one foot above and below that plane as shewn in (Fig. 2). Around this copper tube are two windings of isolated copper wire, and the ends are connected with one of Bunsen’s cells. Inside this tube is a bar of Bismuth A B. at B is attached a string which bears a small weight G, at A another string is fastened which passes over the pulley H to the observer at the telescope where an arrangement is so made that he can raise or depress the Bismuth Bar at will. A continuous current is sent around the tube C D and after seeing that the magnet is not influenced by it, the bar of Bismuth is raised and depressed at proper intervals (so as to increase the deflection of the Magnet) so that alternately the ends A and B are brought into the same plane as that of the magnet. By repeated elevations and depressions Weber has produced a considerable deflection and measured the same. This deflection can only be caused by an induced polarity in the Bismuth Bar. As I said my experiments are by no means fine enough to say if the Bismuth behaves also here as a bar of soft iron would. I do not know either what kind of bar Weber used, whether it was crystallized or not and how long. To make one for myself I poured molten Bismuth into a hot glass tube of about 3/8 of an inch in diameter and 5 inches long; kept it in a state of fusion in a sand bath until all air bubbles were expelled and the bar perfectly solid; I let it cool then very slowly and on taking it out of the sand bath it, on cooling further, broke its glass covering and came out of its shell like a chrysalis – a piece of such a bar sets axial between the poles of the magnet, so that the line of greatest cleavage (for it is all crystallized very regularly) is in direction of the length of the bar – looking at the section of one end it appears crystallized in concentric polygons about the centre or axis of the bar. I could not as yet get a suitable theodolite and mirror so as to give you any certain results.

RI MS JT/1/H/171

RI MS JT/1/HTYP/205–207