ON JLLtJMlNATTON. gj 



at the Institute on Monday last. Count Rumford, at whose 

 <lesh-c I send it, has taken the trouble to revise and correct the 

 translation. 



I am, 

 Paris, Your very humble servant, 



27th March, 1805. W. A. CadeIL. 



No. 17, R'^e de Varenne. 



Amongst the necessaries of life may be reckoned heat and Intiibductjon. 

 light; and each of them composes so considerable an article 

 of e.xpcnce, that every improvement that tends to facilitate 

 their production, or to economise their consumption, is deserv- 

 ing of attention. 



Having made, at different periods, a great number of expe- An improred 

 riments on the production of light in the combustion of in- ^' 

 liamable bodies, and on its distribution ; and having lately con- 

 trived a lamp which, on trial, has been found to answer very 

 well, I have resolved to submit to this learned assembly some 

 of the results of my researches on this Important subject. 



I'he lamp, which I have the honour of presenting to the — «ot esseatl- 

 Institute, has nothing new in the essential part of it, that is, 

 in the form of the wick • for, after the ingenious discovery of 

 the circular wick by M. Argand, it does not appear to me 

 probable that the economy of oil in the production of light can 

 be carried much farther : When this lamp is in good order it 

 gives no perceptible smoke, nor smell ; and hence, I think, we 

 may conclude that the combustion of the oil is complete, and, 

 consequently, that the quantity of light is at its maximum. 

 IJut there still remains much to be done to improve the gene- 

 ral form of lamps, in regard to their elegance and conveni- 

 ence, and abo^-e all, to distribute their light in a more advan- 

 tageous and agreeable manner. 



If the facility with which tlie eye distinguishes objects de- Vision is well 

 pended solely on the intensity of the light by which they are Hom'^^'vIJ? 

 illuminated, the scicntiiic distribution of light would be less different inteu- 

 important; but that is far from being the case. We are able ^'^''''" 

 io see, very distinctly, with intensities of light which are ex- 

 tremely diffierent; provided that the eye has had the time to 

 conform itself to the quantity of light present, and that that 

 quantity remains invariable. 



It 



