IC-6 Objinuitions on Coloured Shadowt. 



even to tell when tlic yellow glnfs w-as before the lamp, and when It was not ; and though 

 the alTiflant often exclaimed at the ftriking brilliancy and beauty of the blue colour of the 

 very fliadow 1 was obferving, I could not difcover in it the lead appearance of .any colour 

 at all. But as foon as 1 removed my eye from the tube, and contemplated the (liadow 

 with all its neighbouring accompaniments, the other fhadows rendered really yellow by 

 the eflcdt of the yellow glafs, and the white paper, which had likewife from the fame caufe 

 acquired a yellowilh hue, the fliadow in quedlon appeared to me, as it did to my alfiftant, of 

 a beautiful blue colour. I afterwards repeated the fame experiment with the apparently 

 blue Ihadow produced in the experiment with day-light and candle-light, and with exadly 

 the fame refult. 



How far thcfe experiments may enable us to account for the apparent blue colour of the 

 (ky, and the great variety of colours which frequently adorn the clouds, as alfo what other 

 ufeful obfervations may be drawn from them, I lc;ve to philofophcrs, opticians, and painters 

 to determine. In the mean time, I believe it is a new difcovery; at lead it is undoubtedly a 

 very extraordinary faft, that the eyes are not always to be believed, even with refpc£l to 

 the prefeiice or abfence of colours. 



I cannot finifli this letter without mentioning one circumftance which ftruck me very 

 forcibly in all thefe experiments upon coloured fhadows, and tfiat is, the mod perfect har- 

 mony which always appeared to fubfift between the colours, whatever they were, of the two 

 (hadows; and this harmony feemed to me to be full as perfect and pleafing when the 

 fhadows were of different tints of brown, as when one of them was blue and the other yellow. 

 In fliort, the harmony of thefe colours was in all cafes not only very flriking, but the ap- 

 pearances were altogciher quite enclianting; and I never found any body to whom I 

 (hewed thefe experiments, whofe eyes were not fafcinated with their bewitching beauties. 

 It is however more than probable, that a great part of the pleafure which thcfc experi- 

 ments afforded to the fpectators, arofe from the continual changes of colour, tint, and (hade 

 with which the eye was amufed, and the attention kept awake. We are ufed to feeing 

 colours fixed and unalterable, hard as the folid bodies from which they come, and juft as 

 motionlefs; confequently dead, uninterefting, and tirefomc to the eye; but, in thefe experi- 

 ments, all is motion, life and beauty. 



It appears to me very probable, that a further profecution of thefe experiments upon coloured 

 (hadows may not only lead to a knowledge of the real nature of the harmony of colours, or the 

 peculiar circumftances upon which that harmony depends ; but that it may alfo enable its 

 to con(lru£l inftruments for producing that harmony for the entertainment of the eyes, in 

 a manner (imilar to that in which the cars are entertained by mufical founds. I know that 

 attempts have already been made for that purpofe ; but when I confider the means em- 

 ployed, I am not furprifed that they did not fucceed. Where the flowing tide, the varying 

 fwell, the crefcendo is wanting, colours mud ever remain hard, cold, and inanimate mafles. 



I am very forry that my more fcrious occupations do not at prefent permit me to purfue' 

 thcfe mod entertaining enquiries. Perliaps at fome future period I may find leifure to rc- 

 fume them '. 1 am, fee. 



Munich, March I, 1793. * 



• Oito Gucrickc, HufTon, Mazcas, Bcguclin, and many other philorophcrs, have piid attention to the coloured 

 fliadow s of bodies which foim the fubjca cf this intcrefting letter. An abridgement of their obfervations 



and 



