146 Management of Light in Illumination. 



the middle of this stopper and its hollow cone is dis- 

 tinctly represented, the brass stopper being distin- 

 guished by diagonal lines. The short brass tube s 

 is likewise shown, which receives the stopper. This 

 tube, which is half an inch in diameter above inter- 

 nally, and somewhat smaller below, is 0.35 of an inch 

 in length, and descends a quarter of an inch into the 

 cavity of the reservoir. 



The brass stopper, which is hollow, has a small hole 

 in its axis which opens a communication between the 

 circular reservoir and the conical chamber above the 

 stopper ; and in the upper part of this conical chamber 

 a small hollow truncated cone is so fixed as to be sus- 

 pended in it. It is through this small cone that the air 

 passes in and out of the reservoir. 



The smaller cone is fixed in the larger by soldering 

 them together before the larger cone is soldered to the 

 brass stopper. 



The secondary reservoir is separated from the cir- 

 cular reservoir by means of a vertical partition r, 

 which is situated immediately behind the short brass 

 tube s, which forms the opening by which the lamp is 

 filled \vith oil. 



Through this partition the extremities of two long 

 horizontal tubes pass, which are concealed in the 

 secondary reservoir and which form the communica- 

 tion between the two reservoirs. The one is situated 

 immediately on the flat bottom of the secondary reser- 

 voir, and extends from the partition r to within about 

 a quarter of an inch of the extremity of that reservoir. 

 The other, which is of the same length, is fixed to the 

 upper part of the secondary reservoir. 



These tubes may be constructed in the following 



