Contributions to Meteorology. Ill 



6 a.m., 2 p.m., and 10 p.m., (by which the civil day is divided 

 into 3 equal divisions of 8 hours each,) and the observations are 

 subjected to the usual corrections for the construction of instru- 

 ments and for temperature. The self-registering principle has been 

 applied to some of them ; and it is matter of regret that more of 

 our observations are not thus supplied, for how scientifically in- 

 correct must be observations on the currents of the wind, for ex- 

 ample, (and which subject is at the present time forming an 

 impoitant point for meteorological investigation in all parts of 

 the world,) unless something better than the mere empirical for- 

 mula of tenths is adopted ? However vigilant the observer may 

 have been, it is not, possible that he can approach even to an 

 approximate estimate of its force or velocity. 



Atmospheric Pressure. — The highest reading of the baro- 

 meter during the year was at 1 p.m. on the 20th December ; 

 and indicated 30.346 inches, and the lowest occurred also in 

 December, on the 31st day, and indicated 28.880 inches, giv- 

 ing a range for that month of 1.466 inches. The average 

 mean range for some years gives the greatest amount in January, 

 next in December. July, for a like period, gives the least 

 range; and July the past year (1857) gave a range of 0.569 

 inches, which is rather less than the average for some years. 

 The mean annual pressure was 29.758 inches, which gives 0.082 

 inches more than the annual mean of the last seven years. The 

 atmospheric pressure for January was 29.915 inches, for February 

 29.915 inches, for March 29.718 inches, for April 29.691 inches, 

 for May 29.682 inches, for June 29.615 inches, for July 29.754 

 inches, for August 29.723 inches, for September 29.842 inches, 

 for October 29.824 inches, for November 29.681 inches, and for 

 December 29.743 inches. 



The greatest barometric range within twenty-four hours with 

 a rising column, was 0.679 inches, on the 8th of February; and 

 the greatest range with a falling column was 0.877 inches, on the 

 27th February. Both these variations occurred at Toronto; the 

 latter happened twenty-four hours sooner there. 



The Symmetrical Wave of November was marked by its usual 

 fluctuations. The final trough terminated at noon on the 23rd 

 day. 



Temperature. — The mean temperature for the year was 40.57 

 degrees, which shows it 0.99 degrees colder than the mean an- 

 nual temperature of the last seven years. The month of Janu- 



