226 On the Horary Oscillations of the Barometer at Rome. 



11 



12 

 1a 

 2 



9903 

 9879 

 9875 

 9828 

 9918 



+ 3 

 24 



— ^4 



— 47 

 4-90 



269.9018 



269.8595 

 269.9018 



18)539.7613 



Mean, 29.9867 



Such is the precise statement; but we shall have a better 

 idea of the general course of the mercury by taking out a few 

 of the best observations and giving them to lOOOths of an 

 inch, thus; 8 m. 29.989 — 10 and 11 m. 29.990— 12.29.988 

 —2A.29.983.4.29.973— 7.29.973— 9 — 29.984— 11.30.001 

 — 12.29.997. Hence we may safely infer, Ist, that the 

 maxima occur very nearly at 11 both morning and evening; 

 26?, that the minimum is at 4 a., after which it remains for 

 some time nearly stationary ; 3J, that the falls are more gra* 

 dual than the ascents ; and, 4^A, that the ranges between the 

 morning and evening maximum is + 0105, and between the 

 afternoon minimum and evening maximum .0278, which is 

 somewhat less than we should have reckoned by Humboldt's 

 table. But there can be little doubt of its approaching the 

 truth, and possibly, had the morning minimum been properly 

 observed, it might have shown a greater range. It is to be re- 

 membered that in the northern latitudes the hours of variation 

 change in summer and winter. These observations were made 

 towards spring, and therefore probably represent very exactly 

 the mean curve. Indeed they coincide remarkably with tl^^ 

 hours found in the tables ; and, notwithstanding any differences 

 which exist between my observations, and those of Humboldt's 

 table, it will be there observed that different series of observa- 

 tions made for several years together do not coincide in the 

 way that might have been looked for, in a path where certainty 

 had been more attainable, and some allowance will therefore be 

 made for these observations of mine, made during a very li- 



