Microscopical Essays, yi 



The wicks are circular, and, the more readily to regulate the 

 quantity of light, are fixed on a brafs collar with a wire handle, 

 by means of which they are raifed or deprefled at pleafure. 



To fix the wick on, a wood mandril is contrived, which is 

 tapered at one end, and has a groove turned at the other. 



The wick has a felvage at one end, which is to be put foremen; 

 on the mandril, and moved up to the groove ; then putting the 

 groove into the collar of the wick-holder, the wick is eafily 

 pufiied forward upon it. 



The wick-holder and wick being put quite down in their place, 

 the fpare part of the wick fhould, while dry, be fet alight, and 

 fulfered to burn to the edge of the tubes ; this will leave it more 

 even than by cutting, and, being black by burning, will be much 

 eafier lighted : for this reafon, the black fhould never be quite cut 

 off. 



The lamp fliould be filled an hour or two before it is wanted, 

 that the cotton may imbibe the oil and draw the better. 



The lamps which have a refervoir and valve, need no other 

 direction for filling than to do it with a proper trimming pot, 

 carefully obfervkig when they are full ; then pulling up the valve 

 by the point, the refervoir, being turned with the other hand, 

 may be replaced without fpilling a drop. 



Thofe lamps which fill in the front like a bird-fountain, muft 

 be reclined on the back to fill, and this mould be done gently, 



that 



