Management of Light in Illumination. 149 



freely to replace that oil ; but the long square tube 

 fixed to the top of the secondary reservoir gives a free 

 passage to the air from one of the reservoirs to the 

 other; and as the stopper, which closes the opening 

 by which the oil is poured into the lamp, is perforated 

 at the point of its double cone with a hole sufficiently 

 large to establish the necessary communication be- 

 tween the air in the circular reservoir and that of the 

 surrounding atmosphere, there is nothing in any of 

 these contrivances that can prevent the lamp from 

 burning well, and consuming the whole of its oil. 



Suppose now that the lamp, properly arranged and 

 burning well, be taken up by its handle and carried 

 about from place to place in the open air. As it 

 cannot be supposed that those into whose hands this 

 lamp must fall, if it ever gets into general use, will 

 have leisure to pay much attention to their manner of 

 holding it, in carrying it about in the course of their 

 business, if the lamp does not take care of itself it can 

 be of no real value ; but a bare inspection of the fore- 

 going figure will be sufficient to show that it cannot 

 be liable to any of those accidents which have hitherto 

 prevented lamps from being portable. 



The very small quantity of oil that can be contained 

 in the vertical burner cannot be thrown out of it by 

 any sudden jolts the lamp may receive in being car- 

 ried in the hand, or on being suddenly set down ; and 

 the concussions which the oil in the circular reservoir 

 may receive cannot sensibly affect that in the burner. 

 That accident has been effectually guarded against by 

 causing the oil to pass through a very small hole in its 

 way from the circular reservoir to the burner. 



As this small hole is made in the side of a tube 



