Lieut.-Col. Sabine's Report on the Meteorolo^ of Toronto. Ill 

 Synopsis of the Annual Variations at Toronto. 



An inference of much practical utility to general observers may be drawn 

 from meteorological observations, made with the frequency which can only 

 be expected at those observatories, where a sufficient establishment is main- 

 tained for the express purpose of observation. We may find that compara- 

 tively a very few observations in each day, at hours not inconvenient in ordi- 

 nary life, may furnish a very close approximation to the mean values and to the 

 annual and diurnal march of the atmospherical phsenomena. Thus from the 

 complete record at Toronto we find, as shown in the subjoined table, that the 

 mean values of the temperature, of the vapour tension and of the humidity, of 

 the pressure of the gaseous atmosphere, and of the whole atmospheric pressure, 

 may all be obtained, with a very near approximation, by a single observation 

 at 8 P.M. (mean time), provided the observation be made with tolerable pre- 

 cision in regard to the hour. By combining with this an observation about 

 sunrise, and another between 2 and 4 in the afternoon, the maximum and 

 minimum of the temperature, of the aqueous and gaseous pressure, and of 

 the humidity, may also be obtained. These hours are by no means inconve- 

 nient for persons whose avocations permit them to keep a register at all ; 

 and appear in every way preferable to a selection which makes 3 o'clock in 

 the morning one of the observation hours. That hour is perhaps the most 

 generally inconvenient for the purpose of the whole twenty-four. The hours 

 here suggested must not however be understood to be of universal applica- 

 tion : they are not so thoroughly suitable, for example, at stations where, as 

 at Trevandrum, the vapour pressure attains a maximum in the forenoon. 



Convenient Jumrs of observation. 



For mean values, 8 p.m. mean time (precise) ; which at Toronto gives the 

 following approximation : viz. — 



o o 



(^Temperature 44*1 Mean annual value 4'4i*4 



At 8 p M at I I^"™idity 78-5 „ „ 78-0 



rp ' ' -i Vapour tension '257 ,■> „ '259 



loronto. barometric pressure . . 29-605 „ „ 29*608 



[_ Gaseous pressure 29*345 „ „ 29*349 



For maxima and minima. 



From 4 to 6 a.m., for minimum of temperature and tension of vapour, and for 



maximum of humidity and gaseous pressure. 

 From 2 to 4 p.m., for maximum of temperature and tension of vapour, and 



for minimum of humidity and gaseous pressure. 



[* Three paragraphs explanatory of the Plates of the meteorological phgenomena 

 described, projected in curves, which accompany the original report, are here 

 omitted.] 



