DECEMBER 1, 1899.] 
burden of upholding the high traditions of 
Great Britain in marine research and ex- 
ploration on the shoulders of her scientific 
men. In their name I appeal to all our 
well-to-do fellow-countrymen in every walk 
of life for assistance, so that these new 
duties may be discharged in a manner 
worthy of the Empire and of the well- 
earned reputation of British Science. 
Joun Murray. 
RECENT PROGRESS IN OCEANOGRAPHY. 
UnbeEr the title ‘On the Laws of Move- 
ment of Sea-Currents and Rivers,’ Dr. A. 
W. Cronander, of the Technical School at 
Noorképing, Sweden, has recently pub- 
lished a volume, giving the results of re- 
searches based upon his observations of 
seo eet rts meter 
rd Pd 
—T Nautical wiles 
currents at different depths, taken in 1875— 
1877 from the lightships in the Baltic, the 
Great Belt and the Sound. Similar obser- 
vations on the rivers Gota Elf and Motala 
Strom in Sweden, in the years 1893-1895, 
are also utilized together with the regular 
daily observations of winds and surface 
¢urrents, recorded on the lightships in the 
Baltic and in the passages leading thence 
to the North Sea. 
SCIENCY. 
803 
These results are certainly very interest- 
ing as they establish the fact that the cur- 
rents in the Baltic obey the winds and that 
none of the other causes, to which we are 
accustomed to attribute motions in sea 
water, such as differences in density and 
temperature, and affluence of rivers, pro- 
duce any currents which are either distinc- 
tive or perceptible. 
Under the assumption that Dr. Cron- 
ander’s investigations are not readily ac- 
cessible to many of those interested in 
these matters, I propose, with his appro- 
bation, to furnish a short résumé to this 
journal. 
Dr. Cronander takes up the question of 
the existence of a current from the Baltic 
into the North Sea, on account of difference 
of level. This difference has been deter- 
mined by precise leveling, between the 
Bothnian Gulf, near Sundwall, and Lev- 
anger, near the Frith of Trondhjem, and is 
0.725 m. On account of the difference in 
specific gravity, which is assumed at 1.027 
in the North Sea, and 1.003 in the Bothnian 
Sea, the difference of level has been calcu- 
lated to be 0.546 m. This would give a 
fall of the Baltic current of 1 to more than 
3,000,000, and since it has been demon- 
strated that with an inclination of 1: 500,- 
000 the motion of water is hardly percep- 
tible, it is concluded that difference of level 
between the Baltic and North seas cannot 
produce any appreciable currents. 
But it has been tacitly assumed that in 
consequence of the great quantities of fresh 
water which are constantly precipitated 
into the Baltic by some 250 rivers (among 
them five of the larger ones in Europe), 
there must exist a surface current, the so- 
called Baltic Current, by which this excess 
of water is carried off into the North 
Sea. 
Dr. Cronander finds two alternate cur- 
rents in the passages leading to the North 
Sea, which are controlled solely by the 
