BAR 



Givcii the temperature oi tin 1 mercury iu. u Barometer, measured by 

 the attached thermometer ; to reduce the observed height to what it 

 would have been at any other temperature, as for instance 32. 



Let b observed height of Barometer, J temperature ; then true 



height at temperature 32o =5 ,^oe Art. -', & x ( 1 TZ^L J 



\ i WOO / 



4. Barometer, range of. 



Annual range of Barometer does not exceed from t to an inch in the 

 torrid zone ; about two inches at Liverpool, the same at St Petersburg ; 



at Melville Island, as observed by Capt. Parry, 1 j^ The extreme va- 

 riation scarcely any where exceeds 3 inches, viz. froiu 28 to 31 inches. 

 In the apartments of the Royal Society (the barometer being 81 feet a- 

 bove low water), during a period of 22 years, viz. from 1800 to 1821, both 

 inclusive, the mean height was 29.86 ; the greatest height 30.77 ; the 

 least height 28.18; and consequently the greatest range 2.59; the mean 

 annual range during the same period was 1.92. The barometer was once 

 observed at Middlewick, as high as 31.00. Greatest height ever observ- 

 ed by Sir G. Shuckburgh, in London, was 30.957. In these climates, the 

 barometer is generally lowest at noon and at midnight The mean height 

 is greatest at the Equinoxes, but greater in summer than in winter. 



5. Barometer, mean height of. 



Mean height of the Barometer in various places, from Erxleben^ and 

 others. ( Young's Nat Phil) 



