i88o.] Modern Advances in Meteorology . 237 
points of the globe is treated of with equal clearness, and 
the causes that tend to modify it are set forth. The influ- 
ence of exposure in promoting rapid and extreme changes 
of temperature, and, on the other hand, of shelter from 
radiation in hindering such extreme changes of climate, are 
commented on ; and it is shown how we may explain one 
of the marvels of ArCtic voyagers, who have frequently 
observed the intense heat of the direct sunshine blistering 
black paint, and making the pitch boil and bubble up in the 
seams of the ship’s deck, whilst all around the snow lies 
thick over the frozen earth, and the temperature in the shade 
is many degrees below freezing-point. Our old friend the 
Gulf Stream, and the service it performs in carrying heat 
across the ocean, thereby rendering habitable these islands, 
which would otherwise be as inhospitable as Labrador, 
claims attention as being but one of a very large number of 
similar ocean-currents, all performing the same great func- 
tion of equalising extremes of temperature and softening 
down the otherwise unendurable rigours of torrid and ardtic 
climates. The account given of the warm and dry winds 
often experienced on the lee-side of a mountain, or range of 
mountains, is extremely instructive. 
The third ledture, on the Barometer and its Uses, is by 
Mr. R. Strachan. Some of Mr. Strachan’s remarks anent 
the popular notions concerning the predicting power of 
the weatherglass are so excellent that we quote them piece- 
meal. 
“ The barometer has always been vaunted as a weather 
oracle, but it really has no pretences to such a dignity. It 
simply shows the statical pressure of the atmosphere above 
it. This pressure must change before there can be any 
variation of the barometer, supposing of course that it is 
kept in the same temperature. The air puts the mercury in 
motion ; hence inertia and fridtion must cause the column 
to change after , not with , certainly not before , the air pressure 
varies. If it be admitted that every wind has its weather, 
then to observe the direction and the force of the wind is 
the first step to observe the weather. Now the wind is a 
dynamical condition of the air, one which we are accus- 
tomed to roughly estimate from our sensation, and it is very 
advantageous to have in addition an exadt measure of the 
statical condition of the air at the same time, which the 
barometer gives us. We gauge then not only the horizontal 
movement of the air, but its vertical mass as well, and with 
the two estimates we are better enabled to judge of proxi- 
mate changes than with either alone. However, the practice 
