1853] ON THE VARIATIONS OF TEMPERATURE AT TORONTO. 15 



hourly, a mean of the observations will not give the true daily perial Academy of Sciences at Vienna in 1850, and are as fol- 



niean, and certain corrections must be applied to the individual lows: — 



ol iservations, deduced frfem the known diurnal march of the tern- Maximum _ Min . mum ngrm^ta^w. 



perature on that day: to effect this the observations at each hour passed through. 



for a series of years are separately collected into monthly ave- Konigsberg August 1 .. .January 9..April2i ...October20. 



rases, and the "means thus obtained are used to furnish by inter- gei-Un (18 years) July 18. . .January 19. .April 19. ..October 21. 



?,! ,, , ,. , , i , t o.;„ „.„., Berlin (92 years) July 22... January 12.. April 17.. .October 16 



polationthe normal diurnal march on each day. In this way Prague (jJ ( o g years) _ July 24.. .January 26. .April 16... October20' 



the normal diurnal curves being constructed for a sufficient uum- Prague (76 years) July 23. ..January 19.. April 15... October 18' 



ber of ]ilaces on each parallel of latitude, the mean curve for that Paris July 28. ..January 15. .April 18 ...October 19' 



latitude is found by graphical interpolation, and from the curves Turin July 27. ..January 3.. April 18... October 26 



c „ .. , iV . J P J-. ,, / , „ f ,, .i • j„ Padua July 26.. .January lo.. April 20.. .October 15 



ot all the latitudes, that for the whole surface of the earth is de- J J ' 



termined. It is thus that Professor Dove has been enabled to These may be compared with the corresponding epochs at To- 

 construct his well known isothermal maps, and to announce those .ronto as derived respectively from the six-years and the twelve- 

 striking results which have astonished and delighted all engaged years series discussed in this paper, 

 in the pursuit of meteorology : I may refer the reader for infer- Toronto ( 1842.5 to 1848.5).. July 28.. Feb'y. 14.. April 19.. October 15. 



mation to Humboldt's Cosmos, to Views of Nature, and to Toronto (1841 to 1852,) July-JS. .Feb'y.12.. April 25.. Octoberl7. 



Dove's Verbreitung der Wdrme, and Brit. Ass. Reports for Tbe anoma i ous character of the North American Winter, so 



1847-8. visible in the Chrono-iso- thermal Plate is also marked by the very 



, „ ,. . . , ... late occurrence of the epoch of the minimum temperature, and 



This principle then of separating the changes of value of the ^ dissimilai . ity ir A hat res pec t f rom all other stations. The 



meteorological elements into two classes-penodic-^r hose t » matic chal . acter of tbis anomalv is father shown by the fact 



winch recur in a determinate order,-and non-per.ochc-or those ^ hou| . - m ^ twent four £ as $ minimum temperature 



which may be considered accidental at he period of occurrence, ^^ ^ ^ md ^ ^ Feb the minimun f 



and whose effect is to be eliminated from the mean result-so fertile earH yi Qn the m of Februa at j? he llour of 2 p. M . ; the 



in results and powerful m analysis, was first brought prominently minhm of ^ j^ rf {he -^ QJ . &om Q p M _ fo ^ £ M _ 



into notice by Bend and Gauss, and has since been applied with ^^ M ^ } yj = n ^ lgft im and ^ ^ 



eminent success by those distinguished philosophers, Dove and Feb thoso of tbe intermediate honr8 on tbe intermediate 



Col. Sabine. . The non-periodic variations are those to which d J d - n ^r sion . The llours from 6 A M _ fo 



the attention of meteorologists will m future be mainly directed g p M iwlus £ or & o * of &6 d ^ their maximum ^ 



in connection with the whole subject ot the wmdrose which re ^^ ^ 20th md 30th rf Ju] those of ^ 



Dove has shewn to be the key of the great problem of china- £ ft . om n p M tQ 5 _ A M -^^ ^ ^ 3rd to ^ ^ 



tolog}. f August. The portion of the twenty-four hours which is 



To proceed now to the paper which is the subject of this warmer than tbe mean temperature of the day varies considerably 



letter. a * different seasons ; in part of November there are fourteen of the 



observation hours colder, and only ten warmer than the mean 



The first table given by Colonel Sabine, contains the tempera- temperature of the day; in the greater part of July twelve of the 



ture of each hour of the day, arranged in monthly means on the observation hours are colder and twelve warmer; and in all the 



average of six years, from 1842 to 1848, and from this by Bes- rest f the year thirteen hours are colder and eleven warmer. 



sel's formula, he has calculated another table giving the correc- On the average of the whole year the mean temperature is passed 



tions to be applied to the observed temperature at each hour of through about 8h. 31m. A.M,and 7h. 44m. P.M., making intervals 



the day, for every five days throughout the year in order to f lib. 13m. and 12h. 47m. The hours from 9 P. M. to 7. A. 



deduce the mean temperature of the day, thus forming the normal m. inclusive, are throughout the year colder than the mean tein- 



diurnal march. His interesting remarks upon this table I give perature of the day; those from 10 A. M. to 7 P. M. are through- 



in full, but the limits of this note compel me to omit his novel ut the year warmer than the mean temperature of the day; 8 



and ingenious idea of chrono-iso-thermal curves. an( j 9 a. M., and 8 P. M., are sometimes warmer and sometimes 



, - , , colder than the mean temperature : 8 A. M. is colder except for 



"From the temperatures computed from the six years of ob- about three weekg m Ju , and 9 A M _ k WMmer t from 



serration we learn many facts regarding the temperature at To- November 20 to March 11 ; 8 P. M. is colder from the middle of 



ronto which are interesting m themselves and may become par- March m , ate m No vember, and either coincides with the mean 



ticularly so in their comparison with the phenomena in other temperature r is slightly warmer during the remainder of the 



parts of the Globe. ,T . . 



" Amongst these may be noticed the following : — The mean The hours of the highest and lowest temperature on every fifth 



annual range, or the difference between the mean temperatures day of the year, and the amount by which the temperature at 



of the coldest and the hottest month, (February and July) is those hours exceeds or falls short of the mean temperature of the 



42 ° .7. The warmest day of the year is July 28, being day may be examined in detail in the Table. From the third 



thirty-seven days after the summer solstice, the coldest day is week of September until April, 2 P. M. is the warmest hour, 



February 14, being fifty-five days after the winter solstice. The with the exception of some days in January and February, 



mean temperature of the year is passed through on April 19th when 3 P. M. is warmer: from April to the middle of May, 



and October 15th. The warmest and coldest days, and the days and again from the end of July to the middle of September 3 P. 



on which the mean temperature is passed through, deduced by a M. is the warmest hour ; and from the middle of May to the 



similar process at Konigsberg by BesseL, at Paris, Turin, and middle of July, 4 P. M. The coldest hour from the latter part 



Padua by Kamtz, at Berlin by Madler, and at Prague by of April to the end of June, and again from the end of October 



Fritsch and Jelinek, are collected by the last named meteorologist to late in November is 4 A. M. ; from the middle of July to the 



in his memoir, — On the daily march of the principal Meteor- middle of October, in January, and for a short time in the middle 



ological elements, deduced from hourly observations at the April it is 5 A. M. ; from the latter end of February to early in 



Prague Observatory, published in the Transactions of the Im- April it is 6 A. M. ; and generally in December and February 7 



