9T% Sckiitijic Intelligence. — Meteorohgy. 



by heat is absolute, and noway affected by the nature of the 

 containing tube. The expansion deduced by the different phi- 

 losophers who have examined it, is here given, omitting the re- 

 results of Sir G. Shuckburgh, as being rather too far from the 

 mean of the others. 



Expansion of Mercury 



from 320 to 212'> Falir. 

 J 

 56 



De Luc, 



Lavoisier and Laplace, - - 55^ 



Hallstrom, . - - - g^ 



Dulong and Petit, _ - - ^^ 



Mean. 



1 

 55^43 



From 1° of Fahrenheit's scale this is equal to ^ -^ or 



•00010023 ; which may be called one ten-thousandth, without 

 the most trifling error in practice. The barometric column may 

 therefore be reduced to the standard temperature of 32° Fahren- 

 heit, by the following simple rule, which will make a table un- 

 necessary: Before the first three figures of the observed height, 

 place two cyphers, multiply by the temperature of the mercury, 

 32°, and subtract the product from the observed height. Ex- 

 ample^ barometer 30.597, temperature of mercury 74°. 



30.597 



TOO 



74— 32° =.00305x42 =1.128 and ^^^^^ . , • u. 



30.469 correct height. 



When the temperature of the mercury is lower than 32°, the tem- 

 perature is to be subtracted from 32°,^and the product of the whole 

 is to be added to the observed height. Thus, let the barometer 



be as before, and the temperature 15 



30.598 



32° — 15 = 17, = .00305 x 17 = .052, and ^^^ 



30.649 correct height. 



J. FOGGO. 



4. Aurora seen in the daytime at Canonmills. — The morn- 

 ing of Sunday the 9th September was rainy, with a light gale 

 from the north-east. Before midday the wind began to veer to 

 the west, and the clouds in the north-western horizon cleared 

 away : the blue sky in that quarter assumed the form of a seg- 



