a Miscellanies. 207 
8, Galle’s Three Comets.—Mr. Galle, assistant observer at the 
Royal Observatory of Berlin, has discovered three comets in the short 
space of three months. 
The first was discovered Dec. 2, 1839; it passed its perihelion J 
4, 1840, and was visible to the naked eye fora ew nights in January 
as a nebulous star ofthe fifth magnitude. 
The second comet was discovered Jan. 25, 1840; ‘it passed its per- 
ihelion March 12, 1840. It was seen at several plac s in the United 
States, without, however, being visible to the naked eye. 
ese two comets are considered as new discoveries. Their ele- 
ments do not agree with those of any that have yet been observed. | 
Their motions may be perfectly represented by supposing them to 
move in a parabola, a curve which does not return into itself: so that 
no plausible conjecture can be formed respecting the time of their 
past or future appearances, except that the period of their revolutions 
cannot be much short of a thousand years. 
The third comet was discovered March 6, 1840; it passed its peri- 
helion April 2, 1840; its tail (visible only in a telescope) might be 
traced through several degrees. Its elements, compared by its dis- 
coverer in connection with Encke, show that it is the same as that 
which appeared in 1097 and 1468, and that its period is about 370 
years. Its two last “appearances occurred in the autumn, when it 
passed much nearer the earth, and hence its greater brilliancy.—Jour. 
of Franklin Institute, May, 1840, p. 358. 
9. New Comet.—The third comet of A. D. 1840, was discovered at 
Berlin, Oct, 26, 1840, by Dr. Bremicker. It was then near 0 Draconis, 
appeared as a faint nebula. Its elements, as computed by Mr. Peter- 
Sen, Assistant Observer at the Altona Observatory, from observations 
taken Oct. 27, 28 and 31, are as follows : 
Passage of Perihelion, 1840, Nov. 15.9154, m. t. Altona. 
Perihelion distance, - - - + 1448 
Longitude of Perihelion, Synine iécierda 95°. At 
. “ Ascending Node, - + 248°31' 55" 
Inclination, oe bot easel, [eee Bee 
Motion direct. 
Astr. Nachr. 412, quoted by S. C. Walker, Esq. in Phil, Nat. Gaz. 
Dec. 24, 1840, ‘ 
10. Manufacture of Glass for Optical Instruments. 
To the Editors of the American Journal of Science and Arts. 
GeNtLEwEN,—Glass is a well known substance, which has been 
made and used from remote antiquity, and the manufacture, like most 
; - 
