William Daniel Conybeare to Faraday   4 April 1823

Brislington nr. Bristol | April. 4.

My dear Sir

I take up my pen rather with the design of expressing my thanks for your obliging attention to my enquiries than in the hope of being able to throw any new light on the difficulties you suggest - & yet even at the risk which I feel I shall incur of only expressing my own ignorance I shall venture a few words on these also - but first permit me to say how flattering I feel the attentions to wh[ich] I have alluded, coming as they do from a person whose merits as a discoverer I esteem of a very high order & whose reputation I am certain will encrease [sic] almost with every experiment he makes -

When I consider how many lurking & unsuspected causes may interfere to prevent the success of an experiment I confess I am inclined to hesitate before I admit the absence of reaction in one of the cases you mention (namely when the wire was in the middle and the pole outside) as yet fully established - in the other case (when the pole is central) my own views w[oul]d have led me to expect the result you found - yet from one circumstance you mention I doubt whether those views are not erroneous. I will first state what those views are -

I have always referred the phenomena to a circular electro Magnetic current revolving round the wire only & tending to drive a particle of north polarity in one direction (say that of the apex of the black triangles in the accompanying diagram) & that part[ic]le of S. pol[arit]y in the opposite direction (towards their base)[.]

The revolution of the magnetic pole round the wire is a necessary corollary - because it is placed exactly in the same circumstances as the single particle above supposed - The revolution of the wire round the magnet I explain thus if a north polar particle +. fig. 2, be brought within the sphere of this current it is as we have seen repelled from the apex of the triangle - and of course it equally repels that apex - hence if + be fixed & the wire movable, the wire will move in the direction from a to b - & as it is always confined at one end must necessarily move in a circle -

On this view there would be no tendency in the nature of the reaction to make the particle + rotate on its own axis - therefore the result is thus far exactly what I should have expected (for I consider the pole of a magnet as obeying the same law as a single polar particle.)

You mention however having produced the rotation of a magnet on its own axis. I have overlooked in some way this experiment[.] Where is it recorded?¹ Where [sic] the circumstances such as would be inconsistent with the above views?

With regard however to the case in which the wire was central it ought certainly according to this view to have rotated on its axis <-> & a priori it appears to me certain that (unless for some obstacle of an extraneous & accidental nature it would do so) - for I will reason thus[.]

Suppose an apparatus were constructed with a great number of wires arranged so as to form a hollow cylinder moving on two spindles Z & C - connected with the Zinc & Copper ends of the battery & the north pole N of a magnet presented; there can I imagine be no doubt that from the action of the pole on each of these wires the cylinder would be made to rotate on its axis -

Now this being the case - suppose the diameter of the cylinder were reduced till all the wires were brought into contact & formed a close fasciculus I cannot conceive why the rotation should not be destroyed by this change[.]

Nor do I see how a single wire differs from such a fasciculus[.]

At any rate I think the phenomena might be greatly cleared up by trying the effect of a cylinder thus composed the wires not in contact - & afterwards a cylinder formed of a continuous sheet of metal -

With regard to my own apparatus I am provoked not by its failure - (for one must be prepared in all new subjects to grope ones way & to learn as much from the failure as the success of experiments) but because I find it impossible to understand the cause of that failure -

I was much interested in the important information you communicate with regard to the liquefaction of Chlorine² &c - you have rendered correct the blunder of a friend of mine who in beginning a course of Chemical experiments sent for a bottle of Carbonic acid -

Our institution at Bristol is now placed on a perman<<ent>> basis - the regulations proposed by the provisional Com<<mittee>> having been unanimously adopted on Monday last. On <<the>> 21. we meet to elect officers - & shall then soon get into active operation - one of our objects is the formation of a philosophical Society - w[hic]h will include honorary members as well as proprietors - if you will permit me it is my intention to have the honor of proposing you as one of these - but I suppose nothing will be done in the business for a month³ -

So much has been accomplished in your Institution that I look w[i]th very sanguine views to the acquisition of a similar instrument of science in our neighbourhood - had it existed twenty years earlier Sr. H. Davy might perhaps have remained amongst us - & the experiments w[hic]h have illustrated your laboratory have immortalised ours -

We have expended our whole capital in our building but desire an annual income from subscription & we are also raising funds from donations to furnish our Museum with cabinets & to provide apparatus - on the latter head I shall be very desirous to consult with you as to the best & most economical forms of galvanic batteries &c - the younger institutions must always look up to the older for assistance & information - believe me My dear Sir | very truly yours | W.D. Conybeare

P.S. Should any thing bring you this way I shall have much pleasure in shewing you every thing interesting in the way of science in this neighbourhood & in affording you introductions to the Iron works of S[ou]th Wales - & shall have a bed at your service -

Address: M. Faraday | Royal Institution | Albemarle Street | London

Postmark: 5 April 1823