Faraday to Edward Sabine   12 January 1853

Royal Institution | 12 Jany 1853

My dear Sabine

I am sorry for your sake that I gave you the trouble of writing again¹; but not for my own, for now I understand clearly the part of the effect to which you wished to draw attention, and am much struck with it, especially with the equality of amount in the different parts of the earth, and still more especially, with the fact as you state it that in a single week after the sun has passed the equator a full half of the whole amount of this annual effect is produced. What with a bad memory & the many calls upon my attention in other directions I find it difficult & headachey work at times, to realize the positions due to this or that particular kind of variation. I wish you could devise such a mode of representing them, either by coloured areas or otherwise, that one could look at any one simply, and then superpose one on another so as to obtain the sum of effect for any given time. My plate of curves² will not help me do this, because the means of the months are made to coincide; and therefore do not help me to see how the variation you now distinguish, combines with that I referred to of the amount of variation at a north or south place at the time of the one or other solstice. If I could succeed in catching experimentally the amount of change in the paramagnetic character of oxygen by a given difference of temperature, as that of 60˚ and 0˚, then I should be encouraged to try & compare the phenomena & the facts again: but I have not succeeded in that yet, and yet worked so hard for that purpose in the autumn, that at last I was obliged to relinquish it from the effect of mere weariness & fatigue. I dare say I shall be tempted to try again after the season is over, if all remains pretty well.

I do not know that I have any right to pretend to speak with any authority, but it seems to me that after your observation of the Solar spots and variation periods;- the determination - separately, & distinction one from another, of such particular phenomena as the variation you now refer to, that presented by the larger disturbances, & the several others which I may express by &c &c, are of the utmost consequence to the development of the physical condition of the magnetism of the earth. And although one may be tempted by the coincidence of sun spots & variations, or by the magnetic condition of oxygen, to try ones powers now & then; yet in fact it is working without the necessary data that are within our reach, if one sets to work before all these distinct variations, or features of variation, are developed, which such comparisons & collections as you have made & are making, can supply.

I am | My dear Sabine | Ever Yours | M. Faraday

Mr. Stokes left me to day after a most beautiful series of demonstrations on Monday & yesterday³ regarding his discoveries. The finer experiments cannot be made in public but some beautiful ones are possible | MF