150 Management of Light in Illumination. 



which is vertical, it is not liable to be stopped up by 

 bubbles of air nor by the sediment of the oil ; and, if it 

 should ever happen to be stopped up by any accident, 

 it can easily be cleared out by means of a small wire 

 introduced by the opening through which the lamp is 

 filled with oil. 



Notwithstanding the smallness of the opening by 

 which the oil passes into the burner, if from careless- 

 ness in carrying the lamp it were held for a consider- 

 able time in such a manner that the extremity of the 

 handle were considerably higher than the level of the 

 top of the burner, so much oil might at length have 

 been forced into the burner as to overflow ; but this 

 accident is prevented by the vertical partition which 

 separates the cavities of the two reservoirs. As long 

 as the lamp stands on its foot or is carried in such a 

 manner that its burner is held in a vertical position, 

 the oil flows freely from one reservoir to the other, as 

 we have just seen; but, as soon as the lamp is leaned 

 forward in such a manner as to cause the end of its 

 handle farthest from the burner to be raised up higher 

 than the top of the burner, the oil in the cavity of 

 the handle is thrown forward against the vertical par- 

 tition, which partition will support this oil and prevent 

 its descending into the circular reservoir. The small 

 quantity of oil contained in the lower square trunk 

 belonging to the secondary reservoir will be emptied 

 into the circular reservoir ; but no more of the oil in 

 this reservoir can follow it, for the farther end of that 

 tube, and also of the air-tube, will now be elevated 

 above the surface of that oil. 



These contrivances effectually prevent the oil from 

 overflowing at the extremity of the burner ; but oth.ers 



