ms 
386 AM. Guinand’s Flint Giass. 
two thousand years ago,) and that the actual joss of heat in 
that period has not produced a variation in the length of the 
day, of the two-hundredth part of a centesimal second. 
Lond. Phlos. Mag. and Journ. 1824. 
15. Zoology.—Baron Cuvier is said to be engaged in pre- 
paring for the press a great general work on Ichthyology. 
. Fine Arts.— Mr. Milbert, a French gentleman whe 
rae anled several years in the United States, as a.naturalist 
in the employment of the french government, is about to 
et in Paris his “Voyage Pittoresque dans PEtat de 
ew-York.” We had the pleasure of examining his port- — 
folio some years since, while he was in this country; and — 
from the specimens there exhibited, we believe that this will 
not be excelled even by his celebrated Travels in the Isle of 
France, a work of a similar nature. . 
17. M. Guinand’s Flint Glass.*—Opticians and astrono- 
mers have long lamented the imperfection of refracting tele- 
scopes, from the fnaposaibility of obtaining flint glass for lenses 
Wotlecdly uopenagnonte without stria, er any other dafecte, 
of sufficient size. These difficulties are - death, 
joiner, and at the age of thirteen became a cabinetmaker. 
Having seen an English reflecting telescope, he procured leave 
to take it to pieces and put it together again. This. gave th the 
first impulse to that object, which afterwards gave ‘him so 
much celebrity. When he attempted to manufacture achro- 
matic glasses, meeting the same difficulties which others had 
experienced, he began (at the age sof 35) to make experi- 
ments on the manufacture of glass. With no advantages, 
except those which his own ingenuity supplied, 
erected a furnace, with his own hands, and continu 
for many years a series of expensive and fruitless exy 
ments, labouring mecqsionely, at some mechanical emp 
sof subsistence, and of purchasing 
wood, and*the etait jsketials for his furnace, his cruci- 
bles, and his glass. He carefully noted the particulars of 
* Abstract of a Tract of 25 pages, 8vo. London 1825. 
