476 
MR. We He WOLLASTON's (BUCKING- 
HAM-STREET) for a# IMPROVEMENT 
i” SPECTACLES, by the aPPLICATION 
of CONCAVO-CONVEX GLASSES to 
them, 
- The object of this invention is to re- 
medy a defect that has long been com- 
plained of in f{peétacles, viz. that no objeéts 
appear diftin& through them but fuch as 
are feen through the centre of the glaffes, 
or nearly fo, but are indiftinét in propor- 
tion to the diftance of the part of the glafs 
through which the} are feen from the cen- 
tre, whether fide ways, or upwards or 
downwards ; that is to fay, the indiftin&t- 
nefs is greater in proportion as the rays 
of light paffing from an objeét to the eye 
ais more obliquely through the glafs.— 
Ar. Wollafton having objerved, that the 
portion of any glafs employed in any one 
pofition of the eye is fmall, he perceived 
that by making the fubftance of a glafs 
curved in the manner of a hollow globe, 
each portion of it might be fituated nearly 
at right angles to the dire€tion of the 
fight, and would thereby render lateral 
objedis diltin&, without impairing the 
diftinétnefs at the centre. Mr. Wolliafton 
has applied this principle in fuch a man- 
ner, that the form of his glaffes is fuch 
that the outer furface of each is {pheri- 
cally convex, and the inner furface (pheri- 
cally concave. For fhort-fighted ‘perfons, 
the concave furface of each glafs is more 
curved than the convex furface, ‘by which 
the rays of light paffing through the fame 
are diverged, and the degree of curvature 
of the concave furface is to be increafed in 
proportion as the perfon is mere fhort- 
fishted. , ey it ya 
For long-fighted perfons, the form of 
each glafs muft be fuch that the convex 
fu: face fhall be move curved than the con. 
cave, by which the rays are converged ; 
and the degree of curvature of the convex 
furface of the glafs is to be increafed in 
Monthly Retrofpef of the Fine Arts. 
[June 1; 
proportion as the perfon is more long- 
fighted. 
Obfervation.—This patent has occafione 
ed fome controverfy between the patentee 
and Mr. Wm. Jones, who not only denies 
the advantages which Mr. Wollafton con- 
ceives to be attached to the menifcus glafs, 
but avers, that fo far from being a new 
invention, he has long been poflefied of a 
fpeftacle glafs made in the form for which 
this patent was obtained. 
I 
MR. JAMES BENNET’S (MANCHESTER) 
for a METHOD of FELTING WOOLLEN 
CLOTH, Gc. 
After the cloth has been manufa&ured 
hy the weaver, and has gone through the 
procefles of cutting, fcouring, and cleanf- 
ing, as if may require, it muft be immerfed 
in hot water, a little below the boiling- 
point. Itis then'to be taken out, and laid 
on a Jarge fligged ftone, placed on a frame, » 
having a roller at each end, for the pur- 
pofe ot receiving the cloth, which muft be 
wound tight over one of the rollers, the 
flag-ftone having been heated with hot 
water. One end of the cloth muft then be 
drawn tight over the furface of the ftone, 
and fixed to the roller at the other end ; 
when fo fixed, hot water, juft below the 
boiling point, muft be poured on the cloth 
as it lies on the ftone, and the furface of 
the cloth is to be rubbed or worked in 
that ftate with a polifhed marble, or fome 
other hard body having'a polifhed furface, 
until the workman perceives a ftiffnefs in| 
the fri€tion, by the cloth becom: g nearly 
dry: the procefs is to be repeated until 
the felt required be produced ; which pro. 
ceffes will produce a felt, and caufe the 
body of the cloth to unite in a found fub- 
ftance.. This method may be ufed either 
with or without foap, but the latter is 
found to be moft beneficial to the fubftance 
of the cloth, which may then be dyed and 
finithed to any colour. ~ 
MONTHLY RETROSPECT OF THE FINE ARTS, 
(Communications and the Loan of all new Prints are requefted.) 
The, EXHIBITION of the ROYAL ACA- 
eyes DEMY, 1804. 
i the exhibition of this year, there are 
fi many goed pictures, though few ‘of 
any very firiking or leading defcription. 
The prefident has ten; No. 30 is marked 
with genius andfpirit. No. 37> the portrait 
of bim/felf, is a refemblance, but we do not 
with to fee his pencil fo employed. *°The° 
Tomb of Archimedes is an-addreis to the 
mind; but, though it may be materially 
altered, we think this picture has been ‘in 
a former exhibition; the fame has been 
faid of his Hagar and Ijfbmael.~ His 
Moonlight, Venus and Adonis, and Phéeton, 
are claflically conceived, ‘and forcibly 
oT sc Ae al ial ta , 
Sir George Beaumont has three pictures, 
which, confidered-as the poda@ion of an 
amateur, are very extraordinary indeed : 
Rsiempegolay ie: Rais they 
