164 Management of Light in Illumination. 



When the upper part of the lamp is to be fixed to 

 its stand, the lower part of the tube b is introduced 

 into the opening of the stand c, and is turned round in 

 the tube c till the hook v, coming to the part of the 

 ring i where it is interrupted, descends through that 

 opening. The tube b, being then turned round its 

 axis to the left nearly one whole revolution, the hook v 

 receiving and embracing the ring z, it is at length 

 stopped by a part of this ring, which is turned down- 

 wards ; and the upper part of the lamp is thus firmly 

 fixed to its stand. 



After having tried several contrivances for fixing the 

 lamp to its stand, this appeared to answer best. The 

 hook v should be placed nearly under the handle of 

 the lamp, in order that when the lamp is fixed to its 

 stand the opening in the ring i may be less in view. 



The projecting ends of the vertical wires, by means 

 of which the hoop h is fixed in its place, are useful in 

 fixing the lamp to its stand, as they rest on the top of 

 the ring i. 



Before I finish my account of this portable lamp, I 

 must say a few words more respecting the different 

 forms that may be given to its wick. 



As the internal diameter of the glass chimney of this 

 lamp at the level of the lower part of the flame must 

 not be more than eight tenths of an inch, it is neces- 

 sary that the flame should be placed as exactly as 

 possible in the middle of it, for otherwise there will be 

 some danger of its touching the glass. To avoid that 

 accident, wider chimneys have sometimes been used ; 

 but, where this has been done, the beautiful white 

 colour of the flame has always been more or less in- 

 jured, and the quantity of light sensibly diminished, 



