Samuel Hunter Christie to Faraday   1 February 1822

Bowater Crescent | Woolwich 1st February 1822

Dear Sir,

With this I trouble you with a copy of my paper on magnetism¹ which if after having read it, you think it will be acceptable, I will be obliged to you to present to Sir Humphrey Davy, should you have an opportunity. I cannot but regret that I should not have been able before this, to pay this mark of respect (if I may be allowed to view it in this light) for so distinguished and zealous a lover and promoter of science.

Since witnessing your very interesting experiments I have again read your account of them², and now comprehend your general views, which owing to my not having seen the previous account I did not on the first perusal; and certainly I feel the justness of your conclusions. You will excuse me for making a few observations, which may not be correct, or at all events be of little value from my not being so much au fait in this part of the subject as I might be, had I performed, or even witnessed, most of the experiments which have been made. There appears to me to be still something wanting in the experiments connected with the rotation of the wires. In all cases of rotation, as far as I have seen, the presence of a magnetic pole appears necessary, whether the pole of a magnet, or the pole of the earth, that is the point to which the directive force tends at any place. Now if there be that complete analogy between electricity and magnetism which is contended for, ought not similar effects to be produced without the introduction of a magnetic pole? Ampère³ contends for the absolute identity of the currents in the conductors and the magnets, and considers this identity proved by the currents in the conductors acting in the same manner on each other as they do on the currents in the magnets, and as these do on each other. Your experiments have however, I think, broken a link in the chain which it appears to me cannot be supplied, unless the same kind of rotary motion can be shewn by means of electric combinations alone, without the presence of a magnetic pole. Until an electric centre of action can be shewn about which a wire can be made to rotate, should we not at least suspend our judgement respecting the identity of the electric and magnetic currents particularly as regards their mode of action? I am not sufficiently acquainted with the nature and management of the apparatus to see how this could be put to the test; perhaps indeed it has been already done. Your explanation is I think peculiarly applicable to the traversing of Ampère’s ring by the action of the terrestrial magnet: I am not however aware that you consider this explanation to apply to the action of one conductor on another. For instance in the case of two parallel conducting wires, which, having counterweights, are free to revolve about parallel axes, the currents passing in the same direction they attract each other, when the axes and currents are not in the same plane; and repel when the currents pass in opposite directions. May not this attraction be nothing more than a tendency of each to revolve round the other as an axis, and the repulsion a tendency to revolve in a contrary direction? Do you view this action in this light? Perhaps the experiment might be varied so as to point out clearly whether it is really attraction and repulsion between the conductors, or a tendency each to revolve about the other. Should the latter be the case would it not supply the link I have mentioned? As I have no opportunity of putting my speculations to the test of experiment, you, who have and can so well do it, will excuse me for troubling you with them, though they may be neither profitable nor amusing; I will therefore not make any apology for it, but conclude with assuring you that I am

Yours very truly | S.H. Christie

P.S. In the very beautiful experiment of the magnet revolving round its axis, might not a strong magnet, coming through the base of the vessel containing the mercury and the revolving magnet, be substituted for the silk attaching it to the bottom, and thus have a continued rotation unchecked by the twisting of the string. If the ends of each of the magnets were slightly convex it appears to me that great freedom of motion would be obtained.