756 



of a millimeter from the mean height deters 

 mined by the observations of 9 h in the mornings 

 and 3 h in the afternoon. M. Herrenschneider 

 observes that in 16 years (1807-1822), the ba- 

 rometric mean of noon differed only 1.8 mm ; and 

 the general barometric mean of Strasbourg 

 only one-fortieth of a millimeter. The follow- 

 ing table presents the results of nine years 

 made at the royal observatory of Paris : 





MEAN 



YEARS. 



of 9 h in the 



of noon. 



of 3 h in the 





morning. 



afternoon. 



1816 



754.13 



753.94 



753.45 



1817 



756.48 



756.16 



755.69 



1818 



756.11 



755.81 



755 22 



1819 



755.07 



754.85 



754.35 



1820 



756.10 



755.85 



755.37 



1821 



756.04 



755.83 



755.36 



1822 



757.48 



757.17 



756.65 



1823 



755.04 



754.78 



754.29 



1824 



755.78 



755.54 



755.05 



Mean of 9 years. 



755.80 



755.54 



755.08 



of a millimeter from the mean of the month. (Bibl. univ., Feb. 

 1824., p. 93) . See an excellent memoir on the horary varia- 

 tions observed at Strasbourg by M. Herrenschneider, among 

 those of the Society of Sciences at Strasbourg, vol. ii, p. 403. 



