Management of Light in Illumination^ 103 



o£ 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, 



