352 ANNUAL OF SCIENTIFIC DISCOVERT. 



tlie month of ^laroh, whon the water rises a foot in each twonty- 

 fi)iir lioiirs, until it n-achcs a Iioiirht of tliirty-live feet above the 

 onliuary levfl. The Amazon is lowest in Ot-rolnT. 



He saitl that the temperature of the whole valley was remark- 

 al)ly even, varying from the miiilMiiim to llic niaxinnun not more 

 than liftcfu ilt-^jjrees. The teniix-iature of the water of (he Ama- 

 zon is also even, the maximum being 84 degrees, ami the mini- 

 mum 78. Other streams show as little variation in this resjjeet. 

 Ill I'onsecjuence of this evenness of temperature, there is u feeling 

 of comfort most agreeable to the inhabitants. 



ASTRONOMICAL AND METEOROLOGICAL SUMMARY. 



Stars of (he Northern Hemisphere. — In the last edition of his 

 " Wunder des Ilimmels," Prof. Littrow gives a summary of the 

 nmnl)er of stars that are in Argelaiuler's charts of the Northern 

 luuiisp here. 



From N. declination .... 0° to 20°, 110,987 stars. 

 " " " .... 20" to 40", ]0:.,0S2 " 



" " " .... 40" to 90°, 108,131 " 



Classified according to magnitude, there are: — 



There are, besides these, sixty nebulae, and sixty-four variable 

 stars. 



Duration of the Flight of Shooting Stars. — Dr. Schmidt, direc- 

 tor of the Observatory of Athens, has recorded as the result of his 

 observations on shooting stars during the last eight years, and 

 especially on the duration of flight of 1,357 meteors out of about 

 16,000 seen. The mean duration of those of different colors was : Of 

 810 white shooting stars, Os. 709; ofoGl yellow, Os.947 ; of 101 red, 

 18.787 ; and of 49 green ones, 2s.G85. The mean of all was 03.92o. 

 As he has been accustomed to estimate small intervals of time, his 

 estimates are deserving of confidence. 



Height of Auroral Arches. — Mr. B. V. Marsh has obtained data 

 for comi)uting the approximate altitudes of three auroral arches, 

 observed in Pennsylvania, Maine, and Massachusetts, on January 

 10, February 20, and February 21, 1865; the estimated altitudes 

 were respectively 97, 80, and 57 miles, — or a mean altitude of 78 

 miles. 



The Skg an Indicator of the Weather. — The color of the sky, at 

 particular times, aflbi'ds wonderfully good guidance. Not only 

 does a rosy sunset presage good weather, and a ruddy sunrise bad 

 weather, but there are other tints which speak with equal clear- 

 ness and accuracy. A bright yellow sky, in the evening, indi- 



