NO. 17.] TEMPERATURE OF THE AIR AROUND THE NORTH POLE. 573 



2. H. E. HAMBERG. La pression atmospherique moyenne en Suede, 1860 

 1895, p. 30, 



3. Osservazioni scientifici .... Duce degli Abruzzi, 



4. NANSEN'S observations at the winter-hut on Franz Joseph's Land, 



5. Atlas climatologique de 1'empire de Russie, 



6. DALL. Alaska, 



7. J. HANN'S Handbuch der Klimatologie pp. 498, 508, 512, 527, 



8. BUCHAN. Atmospheric Circulation. CHALLENGER Report, 



9. Meteorologiske Middeltal og Extremer for Fsereerne, Island og Grenland, 

 Appendix til det Danske meteorologiske Institute Aarbog for 1895. II. Del, 



10. Dr. F. NANSEN'S Durchquerung von Grenland 1888. Erster Teil. Ergeb- 

 nisse der astronomischen, magnetischen, trigonometrischen und meteoro- 

 logischen Beobachtungen. Von Prof. H. MOHN. Ergangzungsheft No. 

 105 zu "Petermanns Mitteilungen". Gotha, 1892, 



and the meteorological observations from SVERDRUP'S Expedition with the 

 Fram, 1898-1902. 



The above remarks about the drawing of the isobars must also be ap- 

 plied to the drawing of the isotherms. I have found the distribution of the 

 temperature in the neighbourhood of the North Pole, given in the charts, by 

 means of sections (latitude = abscissa, temperature = ordinates), along different 

 meridians, the pole in the middle, and the known temperatures from the con- 

 tinents or other stations on each side. Through the points plotted in this 

 way, I have drawn the curve that seemed most probable. 



As regards the greater part of the regions north of the parallel of 60 

 degrees, the charts I have constructed do not show much difference from the 

 recent charts of isotherms with which we are acquainted. Concerning the 

 temperature at, and in the vicinity of, the Pole, the Fram-ohservations are 

 likely to afford a nearer approximation to the truth, than the observations 

 from lower latitudes. I have set forth the reason for the drawing of the 

 isotherms for the interior of Greenland, in the memoir, no. 10 of the above 

 named publications. I regard the strong radiation of heat in the thin air at 

 the high level 1 of this region as the main cause of the low temperature. The 



1 See the "Bathymetrical Chart of North Polar Seas" in the "Norwegian North Polar 

 Expedition, 1893 to 1896", Vol. IV. Edited by FHIDTJOF NANSEN. 



