154 Management of Light in Illumination. 



A small cylindrical wick, similar to those used in 

 Argand's lamp, gives a great deal of very pure white 

 light ; but, as it requires a current of air in the axis of 

 it in order to its performing well, this renders the con- 

 struction of the burner too complicated, and the opera- 

 tion of changing the wick and trimming it too delicate 

 and difficult for common use. It is, however, most 

 certain that this wick produces a very striking and 

 beautiful effect, and many persons have preferred it to 

 all others. 



The wick which has answered best for general use 

 is a flat ribbon wick, about one inch wide, prepared by 

 dipping it into very hot tallow, which, when cooled 

 and cut into proper lengths, is laid by for use. When 

 a new wick is wanted, one of these flat wicks is 

 moulded on a wooden cylinder of about 0.3 of an inch 

 in diameter, and made to take the form of a tube, open 

 on one side from end to end ; and in that form it enters 

 the burner, which is so constructed as to receive it, 

 and also to preserve its form till it is quite consumed. 



The form of the burner is such that a horizontal 

 section of it is nearly in the shape of a horse-shoe, the 

 open part of it being turned towards the handle of the 

 lamp. 



To move the wick, a contrivance has been used, which 

 is not a new invention, but which has been found to be 

 very useful. A strong cylindrical rod of stout wire, a 

 little more than one tenth of an inch in diameter, pass- 

 ing vertically through a collar, formed of several pieces 

 of leather, confined in a small cylindrical brass box 

 soldered to the burner, enters the burner at the bottom 

 of it ; and being fixed at its lower extremity to the lower 

 end of a rack which is placed vertically by the side of 



