34S Limits of perpetual Snow in the North. [May, 



of the snow line at Mageroe would form a point in the Icelandic 

 curve ; for Iceland and Mageroe lie under similar meteorological 

 meridians. 



Some Additional Observations. 



1. Respecting Mr. JuUn's Observations of the Thermometer at 

 Vleoborg, noticed in page 344. 



As Uleoborg lies in the 65th degree of latitude, a collection of 

 12 years' observations in such a place must be very valuable, and 

 deserve some pains to make them as accurate as possible. 



The first observations, says Julin, from 177^ to 17^-? were made 

 by his predecessor, the apothecary Kerborg, with a Florentine spirit 

 of wine tliermometer. Since 1 782 Julin observed himself with a 

 mercurial thL-rmometer made by Hasselstrom, in Stockholm. He 

 took the trouble to compare the Florentine thermometer, degree by 

 degree, with Hasselstrom 's, and by that comparison corrected the 

 whole of the preceding observations. But he still followed the 

 method of his predecessor, and made observations only at six in the 

 morning and six in the evening. Hence his mean temperature 

 cannot l)e correct. 



Mr. Tornsleen, in the Memoirs of the Swedish Academy for 

 1796', has given us a table of the curve of the daily temperature of 

 every month from ten to ten days, as he had found it from ten years' 

 observations at Brunslo, in Jamteland, in the 64th degree of lati- 

 tude. The rate of the temperature difters but little from that at 

 Uieobcrg. But according to this table the yearly mean determined 

 by observations at six in ihe morning and six iii the evening is under 

 the yearly mean determined by observing the extremes of the daily 

 temperature O-G/"^ Reaumur or 1-51° Fahrenheit. This gives a 

 considerable correction. The temperature at Uleoborg for every 

 month, when this correction is attended to, will be as follows:* 



ColKmn 3d re- 

 Julin's table. Ditto corrected. Amount of duced to Fah- 



the correctien. renheit's scale. 



January.. -11 -54° R ....-11-42°R ....0-42° 6-31 °F 



February -10-16 - 9-072 1-088 11-588 



Marcti...- 9-12 - 7-646 1-474 14-797 



April — 3-2 — 2-255 0-945 26-926 



May +2-8 + 3-315 0-515 39-459 



June 9-12 9-5 0-42 53-4 



July 12-16 12-34 0-18 59-76 



August.. 9-92 10-14 0-22 54-81 



Sept 4-06 5-5 0-94 44-4 



October.. 0-96 2-056 1-096 36-626 



November- 5-92 — 5-416 0-504 19-814 



December— 9*94 — 9-14 03 11-44 



♦ I have inserted tljis fable as in the original, to show the rate of the correc- 

 tion; but I have added in the last column the corrected mean temperature at 

 Uleoborg reduced to the degrees of Fahrenheit's thermometer, for the bake of th» 

 English reader. — T. 



