Royal Institution, Jan. 5, 1843.
My dear Sir, - You noticed a short time since, in connexion with Möser's discovery1 (Lit.Gaz. No. 1339, p.650)2, a fact that I had mentioned to you respecting the production upon glass of the forms delineated in a drawing which that glass had been used to protect. That drawing was a view of Rome, in water-colours, by Coke Smyth3, was two years old, and perhaps had remained glazed the whole time. Since then I have observed many similar effects with recent drawings, but none so very striking and perfect as that one. This effect was, I think, without doubt due to the influence of vapour rising from a body and affecting the parts of a contiguous body, influenced by the ever-varying circumstances of heat, cold, moisture, perhaps electricity, &c., connected with the situations of the drawings; and can have no relation as to its cause with effects apparently similar produced by radiating agencies whether of light, or heat, or chemical force. But as the effects of these different causes are likely to be mingled in some of the extreme cases for a while, I was glad of an opportunity lately given me by Mr. Colnaghi, of Pall Mall East, to examine the effects produced by the vicinity of drawings of great age upon glass placed before them. The drawings I refer to were part of the original Lawrence4 collection purchased by Sir Robert Peel, and the glass placed before them was in quality bad, being subject to a very slight chemical action from the atmosphere. Many of these glasses were very dim within, and presented only a mottled and irregular appearance; but on one or two there were striking effects, and especially on that of the drawing of the Crucifixion, by Vandyck5, in which the spear, several of the limbs of the figures, the faces, and parts of the general forms, were very clearly visible on the glass. Now this drawing must be about 200 years old, and yet it reproduced the effect in question.
As Möser's discovery and views have led to the institution and publication of a great number of highly interesting results, it becomes necessary, for the interests of science, to distinguish well between the causes of the effects that may be observed. I will, therefore, suggest, that where effects are attributed to radiating agencies, as in the beautiful results of Daguerre6 and Talbot, and as I understand of Möser, that they be tested by producing some corresponding elementary effect through diaphanous or diathermanous bodies, as glass, rocksalt, &c.; there appears no reason why Möser's radiating effects should not be produced through the latter body. On the other hand, it is very probable, that where the effect has been attributed to radiating agency, whilst really produced by vapour, a diminution of the effect, or a disappearance of it altogether, might occur were the experiment repeated in vacuo, and so a test in this direction also be applied to the results; for a vacuum would certainly not interfere with, but if any thing, rather favour the phenomena dependent on radiation. - I am, my dear Sir, very truly yours, M. Faraday.
BINYON, Robert Laurence (1898-1907): Catalogue of Drawings by British Artists ... Preserved in the Department of Prints and Drawings in the British Museum, 4 volumes, London.
MOSER, Ludwig Ferdinand (1842): “Ueber das Latentwerden des Lichts”, Pogg. Ann., 57: 1-34.
Please cite as “Faraday1459,” in Ɛpsilon: The Michael Faraday Collection accessed on