A Relation of the great effetls of a nerv fort of Burni ng 
Speculum lately wade in Germany ; tah,en from 
the A6}^a Eruditorum of the Month of January 
laft: being a hetter from the Invetitor to the Au- 
thors of that Journal. 
OF the concave burning Speculum which I lately 
caufed to be made in Lujace^ take this following 
Account. 
The like thereof hath not yet been made, that I know 
of^ for in Magnitude it exceeds even that great one which 
'they fliew as a Sight at Paru, and whofe meafure I took 
when I was there, by about three eights of a Lipftck 
£11. The outer Circle of mine is near three fuch £lls in 
Diameter^ and is made of a Copper Plate fcarce twice fb 
thick as the back of an ordinary Knife ; and may therefore 
be eafily removed from place to place, and ordered for 
ufe; whereas thofe which I have yet feen that are large, 
and capable of producing confiderable effeds, being Caft 
thick of a Mixt Mectal, are becaufe of their bulk and 
weight, lefs Tradable. The workmanfhip of this Specw 
lum^ which in one of the other fort, of this Magnitude, 
would be an immenfe Labour, may by the contrivan- 
ces I have invented, be eafily and m little time performed 
by one Man. 
The Pohfh thereof is very good, and r&prefents by dif- 
tind refleftions all thofe appearances which arife from 
the concave Figure thereof j reprelenting a Dwarfe 
like a Gyanr, or the Head or other part of a prodigious 
Magnitude. The Eye being placed nearer the Speculum 
than Is the FQ:m thereof, all ODjefts are feen within it, in 
an 
