215 
burning with the brilliancy of its most vivid light, does nsfe 
diffuse any smell, but if in lowering the wick, it is made to 
burn with a small flame, a strong and disagreeable odour 
will issue from it 
The cause of this phoenomena, may be explained in the 
following manner. As long as the lamp burns lively, the 
current of air in its glass tube is so powerful, as not only to 
cool the wick hole, but also to drive the flame upwards an ( d 
where it is held at a sensible distance, often more than a 
line above the wick hole. The latter is of course so little 
heated, that it does not decompose the oil in contact with it, 
but if in lowering the wick, the current of air becomes 
weak and the flame is no longer propelled upwards, it will de¬ 
scend gradually and finally rest on the border of the wick 
hole. This cannot happen without heating it to a high de¬ 
gree, and as it is continually moistened with oil, its decom¬ 
position explains the cause of the unpleasant odour. 
This defect must necessarily occur in all lamps with a 
metallic wick hole, and we actually know that it is impossi¬ 
ble to construct a night lamp or watch light in oil, which 
is not liable to it. 
After attempting various means to remedy this imper¬ 
fection, the idea suggested itself of giving to the wick hole 
of my new lamp a small projecting edge, to enable it to throw 
off sideways the current of air ascending in the lamp tube, 
and compel it when returning to fall on the flame obliquely at 
a certain height above the extremity of the wick hole, or 
to speak more precisely, above the rising of the edge. 
This edge which is in the form of a funnel, is not more 
than a line in breadth, and answers its object so completely, 
that the wick may be lowered to any desired point, without 
the least unpleasant smell. The flame, whether large or 
small, always continues at a sensible distance above the ex¬ 
tremity of the wick hole, and the latter is never sufficiently 
heated to evaporate the oil which moistens it. 
I need not expatiate on the comfort and pleasure of pcs* 
