Natural Philosophy,-^ Astronomy. 183 
Mean longitude, - - - - 3Sf)°51' T' 
Mean tropical daily motion, - - - 770" 77 83 
Longitude of perihelion, * - - 147° 18' 22 " 
Longitude of node, - - “ 80 45 19 
Inclination of the orbit, - - - 10 37 55 
Log. of greater semi-axis, - - - 0.4421029 
Excentricity, Sin 4° 28' 57".9) - - 0.0781589 
These elements were computed from six oppositions, compared 
with Gauss’s Tables of Perturbations. 
3. Elements of the Or'hii of the Planet Juno. — The following 
elements have been computed by M. Nicolai, Director of the Ob- 
servatory at Manheim : 
Mean longitude at Manheim, Jan. 0. 1819^ 
Mean tropical daily motion. 
Longitude of perihelion^ 
Longitude of node, 
Inclination of the orbit. 
Log. of greater semi-axis. 
Angle of Excentricity, 
117° 45' 2^''.84 
813^^86981 
53° 32'56".09 
171 6 50.23 
13 3 37.29 
0.4263500 
14° 53' 17".44 
4. Geocentric Places of Pallas. — According to M. Dirksen, 
the next opposition of the planet Pallas will be in 1820, Jan. 
6 d 20 ^ 10 ' 41 " mean time at Gottingen, its longitude being 
106'’ 0' 16".2, and geoc. lat. 54° 28' 33".2 south. 
. 5. Baron Zach on the Error of Repeating Circles. — From nu- 
merous observations made by this active and able astronomer^ 
and by M. Inghirami, he has concluded, that an error of from 
five to ten seconds may remain undetected, in the mean of many 
hundred observations with the 12 inch repeating circles of M, 
Reichenbach. 
OPTICS. 
6 . Inclination (f the Resultant Axes of Crystals. — ^The fol- 
lowing measures of the inclination of the resultant axes of cry- 
stals with more than one axis, have been obtained by Dr 
Brewster: 
