A. MATHEMATICS AND ASTRONOMY. 33 



time must elapse before it will be possible to use the rotation 

 of Mars as a standard by which to judge of the invariability 

 of the motion of the earth the problem which Sir William 

 Herschel originally attempted to solve. 



The white spots near the north and south poles of Mars, 

 which are generally supposed to be accumulated snow, have 

 been subjected to accurate measurements by Kaiser, who 

 thinks that the discrepancies in the conclusions of various 

 observers in different years in regard to them is to be found 

 in the hypothesis that these white regions undergo consider- 

 able change of position on the surface of the planet. An?i. 

 Ley den Obs.^ vol. iii. 



AX INCENDIAKY METEOEITE. 



Apprehensions have frequently been expressed concerning 

 danger to property, and to life and limb, from the fall of a 

 meteorite; but very few well -authenticated instances have 

 liitherto been placed on record as to fires being caused 

 by such bodies. We learn, however, from Gaea, that a few 

 moments before the meteoric shower which was so prom- 

 inent in Northern Germany in May last, two fishermen were 

 passing up the River Trave, who saw a meteor fall and strike 

 against a church tower, and rebound upon an adjacent house. 

 This was accompanied by a loud report w^hich roused the 

 town ; and in a few moments afterward fire was observed on 

 the roof of the house, which spread, and destroyed several 

 buildings before it was extinguished. 7 (7, 1873, vi., 356. 



A NEW COMET. 



Through the Smithsonian system of international scientific 

 telesrrams we have received notice of the discovery of a new 

 comet on the 19th of August by Borelli, the astronomer of 

 the Observatory at Marseilles, France. Several errors seem 

 to have been made in the communication as originally pub- 

 lished, which for a few days delayed the astronomers of this 

 country in finding and observing the comet as promptly as 

 was desirable ; and it was announced to be impossible to 

 discover any comet in the neighborhood of the position in- 

 dicated by the figures given in the dispatch of August 19. 

 On the other hand, Professor Hall, at Washington, who 



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