Management of Light m Illumination. 147 



manner. Two slips of tin, each 0.6 of an inch in width 

 and about 5 inches long, may be formed into two square 

 gutters or spouts, 0.2 of an inch wide and 0.2 of an 

 inch deep. One of them being turned upside down 

 and soldered on both its sides to the flat bottom or 

 floor of the secondary reservoir, in the direction of its 

 length, a square tube or trunk will thus be formed. 

 The other square spout is to be fixed in the same 

 manner to the upper part, or to what may be called 

 the ceiling of the long chamber, which serves as a 

 secondary reservoir. 



One of the ends of each of these square tubes must 

 just pass through the vertical partition which separates 

 the two reservoirs, and must be soldered to it; and both 

 these tubes must be open from end to end. 



In order to show in a clear and satisfactory manner 

 the various objects had in view in the contrivance of 

 this machinery (if any thing can be called machinery 

 which produces its effect without any motion of its 

 parts), we will suppose the lamp first to be filled with 

 oil, and then lighted. 



The upper part of the lamp being united to its 

 stand, and the lamp placed on a table, on removing 

 the stopper/* and pouring oil slowly into the lamp, the 

 oil will enter the circular reservoir ; and, as soon as 

 this is filled to the level of the bottom of the secondary 

 reservoir, it will begin to flow into that also, passing 

 through the long square trunk which is fixed down on 

 its bottom. As the air can escape out of this second- 

 ary reservoir through the long square tube which is 

 fixed to its upper side, it is evident that nothing can 

 obstruct the passage of the oil into it, except it be the 

 difficulty that the air in it may find in passing out of 



