396 Miscellanies. 
sected by shallow valleys. Thunder storms are attracted by forests. 
When one arrives at a forest, if it be obliquely, it glides along it; if 
directly, or if the forest be narrow, it is turned from its direction ; 
if the forest be broad, the tempest may be totally arrested. When- 
ever a forest, being in the path of a thunder storm, tends to turn it 
aside, the velocity of the storm seems retarded, and. its intensity is 
augmented. A thunder. cloud which is arrested by a forest, ex- 
hausts itself along it, or, if it pass over, is greatly weakened. When 
a large river or valley is nearly parallel to the course of a thunder 
storm, the latter follows its direction; but the approach of a wood, 
‘or the somewhat abrupt turn of the river or valley makes it pass off. 
A thunder cloud attracts another which is at no great distance, and 
causes it to deviate from its course. There is reason to believe that 
the action is reciprocal. A cloud attracted by a larger, peselegats® 
its motion, as it approaches the principal cloud. When there is 
affluent cloud which was committing ravages, it sometimes sie 
them on approaching the principal mass, which is perhaps a_conse- 
quence of ee acceleration of its course ; but after the union, the evil 
generally increases. Twenty one thunder storms whose course has 
ma qeaetly traced, have extended from N.N. W. to S.5. W. 
No destructive thunder storms have come from any other points of 
the horizon. Lastly, the position and form of the forest of Orleans, 
Blois, &c. satisfactorily accounts for the frequency of hail storms ine ; 
certain communes, and their rare occurrence in others. 
3 5. Aurora Borealis at Paris.—The following are the magnetic 
observations made at the Observatory of Paris, on the Aurora which 
was visible on the night of the 7th of January. The Aurora caused 
a ‘deviation of the magnetic needle in variation. 
A declination equal to 1° 6’ 47”. 
_ An inclination equal to 0° 28’ 00”. 
N. B: The variations of the magnetic needle, in declination, ca” 
baisippreciated to five seconds at the Paris observatory. 
6. Lnghining Tubes.—In the vicinity of the old castle of Rem- 
stein, near Blenkenburg, which stands on a picturesque series of 
rocks, belonging to the green sand, or quadersandstein formation, 
in a loam land, there have been found this summer, very firm and 
long vitre itreous tubes. From a branch in the upper part, two branches 
ome of which are ten feet long, and from these proceed three 
s.—Literary Gaz. Jan. 15, 1831. 
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