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, accelerates 

 its motion, as it approaches the principal cloud. When there is an 

 affluent cloud which was committing ravages, it sometimes suspends 

 them on approaching the principal mass, which is perhaps a conse- 

 quence of the acceleration of its course i but after the union, the evil 

 generally increases. Twenty one thunder storms whose course has 

 been distinctly traced, have extended from N. N. W. to S. S. 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, Stc. satisfactorily accounts for the frequency of hail storms in 

 certain communes, and their rare occurrence in others. 



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, can 

 be appreciated to five seconds at the Paris observatory. 



6. Lightning 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 vitreous tubes. From a branch in the upper part, two branches 

 go off, some of which are ten feet long, and from these proceed three 

 small branches. — Literary Gaz. Jan. 15, 1831. 



