My Dear Sir,
I was only yesterday favoured with your letter of the 4th March <1> in consequence of its coming in a parcel by Sea.
I have long been occupied with the subject of the calorific rays of the Spectrum; and Mr Powell <2> in his Report on Radiant Heat has published several views & results which I communicated to him, and which anticipate some of these of Melloni. <3>
As soon as the Sun will permit me I mean to begin my Solar Expts here on a great scale, and I shall gladly make the Experiments you mention. I have fortunately in this house an uninterrupted passage of 95 feet which gives me a Solar ray of great length and admits the application of a Five Foot Telescope. <4>
I am so much engrossed however with country pursuits, that I find them as hostile to the continuity of physical enquiries as your Parliamentary and other occupations must be. I expect too to be called to give evidence in the lighthouse Committee <5> to which I trust you belong. It will be very odd if the only member of the house who knows anything about Light shd not be on the only committee on light that was ever formed.
I have just been trying but in vain if can [sic] see Microscopic Cleavages in Mica. <6> My Microscopes are excellent, but I can see only a granular structure like that of organised Fluids coloured with red and green patches. You would oblige me by sending me a morsel of your burnt Mica which exhibits the cleavages.
Have you applied the Phenakistiscope <7> disc to the examination of the sparks produced by stirring a wood fire, or from gunpowder and various pyrotechnic compositions. The effect is beautiful. So is it also when applied to driving snow or rain, to cascades of water and to flickering and shooting flames. I expect some curious results in applying it to falling stars & meteors, to the rapid motions of the Aurora & to lightening.
I observe that you have applied the revolving mirror to photometrical researches. I have long ago contrived a Photometer in which a regularly graduated shadow was produced by rotation, & I think a notice of it was published by Mr [Fosse?] to whom I communicated it. Your contrivance is I doubt not much better than mine.
I am My dear Sir Ever Most Truly yrs
Belleville by Kingusie
March 12th 1834.
1. Letter not located.
2. Prof Rev Baden Powell (1796–1860), mathematician.
3. Macedonio Melloni (1798–1854), Italian physicist noted for his discoveries relating to radiant heat. He published numerous articles on the polarisation and refraction of what became known as the infrared part of the spectrum. For a complete list see Royal Society Catalogue of Scientific Papers.
5. Brewster had devised a lens-based lighting system for lighthouses and fought without success to get his system accepted by the Northern Lighthouse Board. In consequence of his complaint about the Board’s conduct, a Parliamentary Select Committee was set up in 1834 to review all the lighthouse boards.
6. These exist at a molecular level, each pair of silicate tetrahedra sandwiching a layer of cations.
7. A device invented in 1832 by Joseph Antoine Ferdinand Plateau (1801–1883), of Ghent, and independently by Professor Simon Ritter von Stampfer of Vienna, who called his the ‘stroboscope’. Plateau studied the motion of a vibrating body through equidistant radial slits in a rotating disc. His ‘phenakistiscope’ or ‘phenokistoscope’ consisted of two discs mounted on a spindle on the same axis, the first with equidistant slots around the edge, the second with concentric circles of drawings of successive action. When the discs spin (in the same direction), and the images are viewed in a mirror through the slots of the first disc, an illusion of movement is obtained. A forerunner was Faraday’s Wheel, the discs of which spin in opposite directions.