Faraday to Peter Henry Berthon   16 October 1857

Royal Institution | 16 Octr. 1857

Sir

A slight suspicion of the point you mention in your last letter¹ regarding the fog bells occurred to me and I refer in my letter² to the arrangement “as a source of force more convenient & available than any other which can be conveyed to a given station,” but I observed that no such reference is “mentioned in the description”: and none occurred to me, because, as the clock must be wound up by a man, & as a man must be at it to set it a going when required for use (for the electrical battery as described would not do that), so I concluded that a man would be in charge of it & therefore that it would be placed where men were.

But if such an application is intended as you suppose then it is not fair to ask for an opinion where no data are given. Are the rocks near the shore or are they distant will not the constant [two words illegible] of a man in the vicinity be required. Will the man in charge of the battery be within hearing of the bell in all states either of fog or surf or wind or other sources of noise. Unless he hears the bell he cannot be sure the apparatus is acting for there is no other means of communication with him; the current may be completed by the clock & go on regardless and yet the bell arrangement not be at work. If the hammer be heavy & the spring strong the battery may sink in power so as not to have sufficient pull upon the arm to be attracted & yet the working on shore continue so as to give no notion to the attendant. He must go to the rocks to wind up the clock (for the battery will not do that) and if the clock is not always to be going then he must also go to the rocks when the fog comes on to set it a going or if the clock be on shore which is not indicated in the description of the apparatus it may go on regularly & yet not be working the bell apparatus[.] Every fresh place for its application might suggest new questions and yet not one such place or even the idea generally is mentioned in the description that I saw. If such an arrangement is proposed to be made at any particular situation the apparatus should first be tested for the necessary force as described in my former letter; and if satisfactory in that respect its fitness for the peculiar place should then be tried experimentally, as to distance, isolation length of wires, &c upon the shore or elsewhere in a situation like as to noise & other circumstances[.]

I am | Sir | Your Very faithful humble Servant | M. Faraday

P.H. Berthon Esqr | Secretary | &c &c &c