Management of Light in Illumination. 153 



burner by the pressure of that in the trunk; and 

 although this accident could seldom have happened, 

 yet I was very glad to have found means to prevent it. 

 Its effects indeed could in no case have been very dis- 

 agreeable ; for, as all the oil that could have possibly 

 overflowed at the extremity of the burner must neces- 

 sarily have run down on the outside of it, and fallen 

 into the reservoir in the foot of the lamp, it could 

 never have been seen, and much less have been spilled 

 in such a manner as to run out of the lamp. That is 

 an accident which I conceive to be quite impossible to 

 happen with this lamp ; and such is my security on 

 that head that I frequently take a portable lamp filled 

 with oil with me in my carriage when I travel, and 

 place it, and not always perfectly upright, in one of the 

 pockets, not lighted, to be sure, but ready to light 

 when I arrive at an inn where I mean to spend the 

 night. It is true that in these cases I always take care 

 to draw back the wick and to close the opening of the 

 burner with a fit stopper, but the opening by which the 

 air enters the reservoir is never closed. 



The burners of these portable lamps have been 

 made of various forms, and wicks of different kinds 

 have been employed. As it will always be necessary 

 to use glass chimneys with these lamps, in order to 

 prevent their flames from being deranged by the wind, 

 such forms must be chosen for their burners as are 

 well adapted to these chimneys. For common use a 

 form must be chosen which will render the operation 

 of trimming the lamp as easy as possible. A flat wick 

 is the easiest trimmed ; but that form is not well adapted 

 to a cylindrical glass chimney, neither is it favourable 

 to the production of light. 



