Management of Light in Illumination. 103 



of the subject to society, I took great pains to make 

 myself thoroughly acquainted with lamps, and with 

 the causes of their imperfections ; and I made a great 

 many experiments with a view to improve them. 

 These researches employed my attention occasionally 

 during several years, and in the prosecution of them 

 I actually caused to be constructed more than one 

 hundred lamps (all differing from each other more or 

 less), as I found to my no small surprise on counting 

 them, as they were taken away from a store-room to be 

 carried into another house, on changing my lodgings. 



I mention this circumstance merely to show that the 

 subject I have undertaken to treat in this Essay has 

 not been taken up hastily, but that it has long been 

 an object of my meditations, and that I have spared 

 neither pains nor expense in its investigation. If I 

 have not published the results of my numerous experi- 

 ments, it is because those results were not sufficiently 

 important to- merit the attention of the public. They 

 were useful to me, for they made me acquainted with 

 facts with which it was necessary that I should be 

 acquainted, in order to be duly qualified to propose 

 improvements in the construction of lamps ; but their 

 details could not fail to be tiresome to readers in gen- 

 eral. 



By far the greater number of the lamps I caused to 

 be constructed in the course of my experiments were, 

 however, rather rude sketches than finished contri- 

 vances. They were designed for making particular 

 experiments, and never could have been employed for 

 any other purpose. 



The results of these experimental investigations en- 

 abled me to contrive two lamps, for different purposes, 



