LOCAL CLIMATOLOGY. 



99 



Or, referring to their distribution for the months, and denoting the 

 polar current P. C, and all others by the letters indicative of their direc- 

 tion, as NE., SE. and SW., we have: 



Current. 



Jan. 



Feb. 



Mar. 



April . 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



P.O... 



38.5 



34.5 



44.5 



36.5 



32.5 



29.0 



30.5 



31.5 



27.0 



31.0 



29.0 



34.5 



NE.... 



6.0 



5.0 



4.0 



7.0 



10.0 



5.5 



8.0 



4.5 



7.5 



7.0 



5.5 



8.0 



SE.... 



4.5 



3.5 



5.0 



6.0 



12.0 



11.5 



14.0 



14.5 



11.0 



10.0 



8.0 



6.0 



SW. .. 



39.0 



80.0 



23.0 



23.5 



23.0 



21.0 



21.5 



23.5 



25.5 



27.5 



31.0 



27.0 



It will be observed that the greater proportion of the southeast winds 

 are from April to November. Some of these are doubtless not South 

 Atlantic currents, but mere "sm breezes " from the lake. So also a part 

 of those reported as polar currents, during the summer months, are only 

 ^Hand breezes " due to the influence of our lake. Deduct these from the 

 polar currents and it would leave the equatorial cm-rent in the predomi- 

 nance from April to December, as stated above. 



It should also be remarked that of the winds reported "south," a large 

 portion of them were a few degrees west of south without being south- 

 west. And besides this the direction of our lake from south to north 

 would give us a south wind, when otherwise we should have a wind from 

 the southwest. 



4. The number of days between the time when the temperature reaches 

 the average in spring, April 23d, and the time when it reaches it in the 

 autumn, October 23d, is also greater by ten or eleven than the number 

 between October 23d and April 23d; the number being in one case 177, 

 and 188 in the other ; that is, our summer half of the year is eleven days 

 longer than our winter half This is doubtless owing to the influence of 

 the lakes. 



We are, however, indebted to this influence for more than the eleven 

 days thus indicated ; for, although if the temperature were determined 

 by length of day and altitude of the sun alone, the number of days in 

 the year which are above the average line would be just the same as 

 those that are below it ; yet when we take into the account the correc- 

 tion for " absorption," it will be found that the number of days below 

 the line will be somewhat in excess of those above it, and the causes 

 will be greater the higher the latitude, until we reach the polar circle, 

 and it then gradually reaches to zero — the value which it has at the 

 equator also. 



