GLASS CELL CUTTING. 213 



for securing the glass slip; a camel's-hair pencil, previously 

 dipped in japanners' gold-size, is then taken between the 

 finger and thumb, and held as represented in the woodcut, 

 when the wheel is put in motion, and a perfect circle is 

 rapidly formed ; the cell is then removed and put aside to 

 dry. In the same way, by securing a sheet of thin glass 

 under the brass springs, and substituting for the pencil 

 a cutting diamond, a circular cover may be readily cut 

 out. A cutting diamond is not only useful to the micro- 

 scopist for the above purpose, but also for writing the 

 names of mounted objects on the ends of the glass slides. 

 A glazier's diamond for cutting glass slides is both conve- 

 nient and economical : the mode of using it may be acquired 

 in any glazier's shop. 



Cutting glass ceils. — Mr. H. H. Brown has also con- 

 trived a brass plate for cutting out the centres of pieces of 

 thin glass, to form very shallow cells. It consists of a thin 

 plate of brass, perforated with holes corresponding to the 

 diameter of the cell required, and counter-sunk to a suit- 

 able thickness. To use it, it must be heated, and a little 

 sealing-wax or shellac melted into the counter-sunk parts ; 

 on this, while hot, the disc of thin glass is to be firmly 

 pressed. When cold, the centres may be easily removed 

 with a common rat's-tail file, the edges being afterwards 

 smoothed over by a fine watch-maker's file. The plate 

 must once more be heated and the glass rings removed, 

 and finally be cleansed from adhesive wax by a little ether. 

 Mr. Brooke has long made use of a small brass press for 

 the purpose of cutting out thin circles of glass and con- 

 verting the same into shallow cells. 



Cells for mounting objects may be made of vulcanite 

 by slicing-tubing made of this material. Glycerine does 

 not act upon it. Mr. Henry Lee uses cells cut from tubes 

 of cardboard; these he finds very useful for mounting dry 

 and opaque objects. Both have the great advantage of 

 cheapness — the former are sold for about 3d. a dozen and 

 the latter Is. a gross. Mr. Suffolk devised a cheap tin-cell, 

 which must partially supersede the more expensive glass- 

 cell; it appears to answer equally well for fluid or dry 

 mounting. The metallic rings for making these cells 

 are manufactured in various sizes and thicknesses by 



