114 
.MR. H. N. DICKSON ON THE CIRCULATION OF THE 
during the early part of 1896 led to increased strength in the European stream, 
resulting in the delivery of unusually large quantities of warm water by the Norwe¬ 
gian stream, with subsequent excessive melting of Polar ice. Hence at the end of 
1896 the northern seas were covered with water below the average temperature. 
But the characteristic of the first half of 1897 is the relatively high pressure persist¬ 
ing in this region, and the deflection southward of the main cyclone tracks, which is 
therefore probably the result of the low surface temperature in autumn, prolonged 
automatically by the weakness induced in the drift circulation. The presence of 
unusual quantities of warm water below the surface would, on the other hand, keep 
up the melting and retard the formation of ice, and temperature would be above the 
average in the higher latitudes, but below it in the regions usually free of ice because 
of the spreading of the ice-cold water. The influence of the warmer water would 
become gradually more apparent at the surface late in the winter, as the colder waters 
Vv^ere absorbed by mixture. 
The weakness of the Norwegian stream in 1897 and the comparatively oj)en sea 
left in the preceding winter resulted in less melting of ice, and, consequently, a more 
limited distribution of Polar water ; hence in the autumn the warmer water appea.red 
more at the surface, and the result is relatively low pressure over the northern sea 
areas and a rapid development of the drift type of circulation. 
The main result obtained by Petteessox is accordingly confirmed, but the jjroblem 
is complicated by the varying influence of the high-pressure areas to the south and 
over the land. The key to the position seems to be the Atlantic anticyclone, which 
controls the low-pressure areas, both directly and indirectly, by its far-reaching eftect 
on the oceanic circulation; and it seems scarcely likely that the causes modifying 
tliis system are confined to the Atlantic, even if they are to be found at the surface 
at all. 
Notes and PvEfekexces. 
1. Geographische Mittheihmgen, 1870. An Englivsh translation of this paper was 
published by the U.S. Hydrographic Oflice in 1871, Avith appendices con¬ 
taining a very complete account of the literature of the subject to date. 
2. Thomsox, WirviLLE. The Atlantic. 1877. 
3. See PiLLSBURY. Report of the U.S. Coast Survey, 1890 ; also Lixdexkohl, 
in Petermann’s Mittheihmgen, 1896. The researches of the Peixce of 
Moxaoo, published in the Comptes Bendus since 1892, should also be 
mentioned. 
4. Krummel and Boouslawski. Gzeanographie, L, p. 268. 
5. Scottish Geographical Magazine, 1888. 
6. Meteorological Office, 1884 and 1897. 
