115

J. is a small cage made of wire of plati-num, of one-seventieth or one-eightieth ofan inch in thickness, fastened to a wire forraising it above the wick, for giving light ininflammable media, containing too little airto be explosive.

h. is a similar cage for placing in the bot-tom of the lamp, to prevent it from beingsmoked by the wick.

C. is a lamp of which the cylinder is cop-per of one-fortieth of an inch in thickness,perforated with longitudinal apertures of notmore than the one-sixteenth, of an inch inlength, and the one-thirtieth in breadth. Inproportion as the copper is thicker, the aper-tures may be increased in size. This formof a lamp may be proper where such an in-strument is only to be occasionally used, butfor the general purposes of the collier, wiregauze, from its flexibility, and the ease withwhich new cylinders are introduced, is muchsuperior *.

I>. is a lamp fitted with a tin-plate mirror

* In the first lamps which I made on this plan, theapertures were circular; but in this case their diameterswere required to be very small, as the circular apertureis the most favourable to the transmission of flame.

i 2