Mr Sivright’s Method (^maMng 
The most common method is to take up with the point of a- 
wetted wire several small fragments of crown glass, and to 
hold tliem in the flame of a candle till they fall down in the 
form of a sntall globule. Another method consists in drawing 
out a thin strip of glass into threads, and holding the extremi- 
ties of the threads in the flame of a candle till round globules 
are formed upon them. These globules being carefully de- 
tached, are placed between two plates of lead, copper, or brass, 
the fractured part being carefully kept out of the field of view. 
The method recommended by Mr Stephen Gray, of making 
microscopes of drops of water, can be considered in no other 
light than as an amusing experiment; and the single micro- 
scopes made by drops of transparent varnish, upon one or both 
sides of a plate of glass, as proposed and tried by Dr Brew- 
ster, though they give excellent images, are still deficient botli 
in portability and durability. 
The defect of the glass globules formed by the ordinary 
methods is, that we cannot increase their diameter beyond a 
very small size ; — that it is difficult to give them a perfect figure ; 
and that there is considerable trouble in fixing them in the brass 
O 
or copper after they are made. 
The following method recently proposed and executed by Mr 
Sivright, is free from the greater part of these defects, and we have 
no doubt will be considered as a valuable acquisition by those 
who either cannot afford to purchase expensive microscopes, or 
who are at such a distance from an optician that they cannot 
be supplied in any other way. 
Take a piece of platinum leaf, about the thickness of tinfoil, 
and make tw o or three circular holes in it, from ^^^^th to th of an 
inch in diameter, and at the distance of about half an inch from 
eacli other. In tlie holes put pieces of glass, which will stick in 
them without failing through, and which are thick enough to fill 
the apertures. When the glass is melted at the flame of a candle 
with the blowpipe, it forms a lens which adheres strongly to the 
metal, and the lens is therefore formed and set at the same time. 
The pieces of glass used for this purpose should have no mark 
of a diamond or file upon them, as the mark always reraains,^ 
however strongly they are heated w-ith the blowpipe. 
The lenses, which were made larger than j’yth of an inch, 
were not so good as the rest, and the best were even of a smallcj:- 
