352 M. Haidinger on the Phenomena attending 



our atmosphere whenever an air-current is progressing at the 

 rate of 92 miles (English) per hour. A point on the equator, 

 by diurnal rotation progresses at the rate of 1464*7 Vienna feet 

 per second without disturbance of the atmospheric equilibrium, 

 on account of the general atmospheric pressure being nearly 

 equal in places lying very near each other. According to Sir 

 John Herschel, the movement of a " devastating hurricane u is 

 equivalent to a pressure of 37*9 lbs. Vienna (32*81 lbs. English) 

 weight, on one square foot Vienna measure. The atmospheric 

 pressure ( = 32 feet of water) on one Vienna square foot is 

 1804*8 lbs., or, compared with that of the most powerful hur- 

 ricane, as 55 to 1. 



I am glad to see these details, as I give them from sources 

 most within reach, confirmed by Prof. E. E. Schmidt's, of the 

 University of Jena, in his copious and excellent 'Manual, of 

 Meteorology' (vol. xxi. of the Allgemeine Encyklopadie der 

 Physik), edited by Dr. G. Kersten and other eminent physi- 

 cists). The following synoptic Table, calculated by Mr. Rouse 

 (Report of the Tenth Meeting of the British Association, held 

 at Southampton in Sept. 1846, p. 344) is found on page 483 of 

 Prof. Schmidt's Manual :— 



Velocity of wind. 



Pressure per 

 square foot in 

 lbs. avoirdupois. 



Character of wind. 



English miles 

 per hour. 



English feet 

 per second. 



60 



80 



100 



913-916 



88-02 

 177-36 

 146-70 

 1340-0 



17-715 



31-490 



49-200 



1 atmosphere. 



Great storm. 

 Hurricane. 

 Destructive hurricane. 



The wind-scale of the Smithsonian Institute (published by 

 the Smithsonian Institute, Nov. 1853, Washington, p. 173) 

 offers analogous results. 



It is the best proof in favour of the use of such extensive and 

 elaborate synoptic works as Prof. Schmidt's Manual, that they 

 gave me complete confidence in the data I had so laboriously 

 compiled from other sources, and this, thanks to the author's 

 kind attention to me, just at the moment when I felt most in 

 want of such. 



"What is the state of the single particles of air composing our 

 atmosphere in the elevated regions, where meteorites, first en- 

 tering it, are capable of producing luminous phenomena as 

 intense as observed at New Concord, even at the enormous 

 altitude of 40 English miles ? In these elevated regions the 

 temperature may probably not exceed that of the interplane- 

 tary space, i. e. 100° lleaumur. Movements of particles 

 may be supposed indeed to take place in the higher regions 



