412 
POPULAR SCIENCE REVIEW. 
temperature from the earth for 2^000 feet above it ; and on 
another day^ in the same week_, the change of temperature 
after the sun had set_, was very small up to 3^000 and 6^000 
feet. From these results^ it seems probable that, for some time 
after sunset, the temperature may increase instead of decrease, 
for some distance from the earth; but no experiments have, 
as yet, been made at night. 
The results as found in winter, spring, and autumn, do 
not accord very closely with those found in summer, and 
therefore all the results cannot, as yet, be combined to deduce 
general laws. In winter, on January 12th, a stream of air one 
mile in thickness was passed through of higher temperature 
than then on the earth. It was a strong current of air, about 
a mile in height, passing from the south-west, and moving 
differently from the stream of air on the earth^s surface ; above 
this warm stratum the air was very dry, and higher still fine 
granular snow was falling into the warm air beneath. 
The meeting with this south-west current of air, which 
was watched for several days afterwards, moving in the same 
direction, what direction soever the wind was below, is certainly 
of the highest importance to us. It bears directly on our very 
high mean temperature in winter, so much higher than is due 
to our geographical position on the earth^s surface, and it is 
very highly probable that to its fluctuations the variation of 
our winters are due. 
The high winter temperature has hitherto been referred, 
for the most part, to the influence of the heated water of the 
Gulf-stream ; but if this was the case, the same agency being 
at work around the coasts of France should exercise the same 
warming influence ; yet we know that the winters of France are 
more severe than our own. 
Upon this matter. Dr. Stark, of Edinburgh, in writing some 
years since on the mildness of the winters in Britain, attributed 
them to the prevalence of the south-west or anti-trade wind, 
which is the prevailing aerial current in Britain during winter. 
He remarked, that as long as these winds blow, we experience 
no frosts nor intense colds ; but the moment the wind changes 
during winter to an easterly, north-easterly, or northerly 
direction, we have both frost and snow ; and more or less 
intense cold. The south-west winds in their course meet 
with no obstruction in coming to us, but blow directly to 
Norway, and to us over the level Atlantic; and hence, it seems 
probable, we enjoy a much milder climate during winter than 
any other countries not similarly situated with respect to such 
winds. 
The south-west winds cannot reach France till after they have 
passed Spain, and crossed the high and cold mountain range 
