1825.] JScientific Notices-^Miscellaneous, 395 



of periods even of very remote date. The author then gives a 

 table of the extreme temperatures observed at Paris, from which 

 there results that, in the second half of the kst century, the 

 greatest cold (23-5° cent.) took place in the 25th January, 1795, 

 and the greatest heat (38*4°) on the 8th July, 1793. He then 

 gives the temperatures observed during the expeditions of Cap^ 

 tains Parry and Franklin, and the dates of the natural congeiar 

 tion of mercury, together with the tables of the maximum tem- 

 peratures observed on land, the maximum temperatures of the 

 atmosphere observed on the open sea at a distance from the 

 continents, and of the maximum temperature of the sea at its 

 surface. From these observations together M. Arrago draws 

 the following conclusions : 1st, In no part of the earth on land, 

 and in no season, will a thermometer, raised from 2 to 3 metres 

 above the ground, and protected from all reverberation, attain 

 the 46th centigrade degree ; 2dly, In the open sea, the tempe* 

 rature of the air, whatever be the place or season, never attains 

 the 31st centigrade degree ; 3dly, The greatest degree of cold 

 which has ever been observed upon our globe, with a thermo- 

 meter suspended in the air, is 50 centigrade degrees below 

 zero ; 4thly, The temperature of the water of the sea, in no 

 latitude, and in no season, rises above 30 centigrade degrees. — 

 (Ann. de Phys. et de Chim.) 



16. Light of Haloes, 



.. M. Arrago, from observations made on the 11th April, 1825, 

 with the instrument v>^hich he has invented for the examination 

 of polarized light, has discovered that the light of haloes (lumi- 

 nous circles which sometimes appear round the sun, and whose 

 apparent diameters are 22|° and 45°), is not a reflected, but a 

 refracted light; a result which gives much probability to, the 

 explanation of the phenomenon proposed by Mariotte. This 

 philosopher supposed that the solar ray is refracted in it^ passage 

 through the drops of water frozen and suspended in the atmo- 

 sphere. M. Arrago is of opinion, that the observation of 

 haloes might lead to the discovery of the true law of the.decrease 

 of temperature in proportion as we rise from the earth's surface, 

 a law which hitherto has had no other foundation than, a single 

 ^.erostatic ascension of Gay Lussac. — (Bullet. Univ. May;,^f^^^.) 



17. On Aerolites. 



Mr. Rose of BerHn has succeeded in separating, from* oi large 

 specimen of the aerolite of Javenas, well marked crystals of 

 augite, of the figure 109 of Haliy's Mineralogy. The same 

 specimen appeared also to contain crystals of felspar with soda, 

 that is, of aibite. He also finds, that the olivine of the Pallas 

 meteoric iron is perfectly crystallized, and that the trachytes of 

 the Andes, like the aerolite of Javenas, is mixed with augite and 

 aibite, — (Edin. Phil. Journal.) 



