President' s Address. 
215 
in Britain. A small portion of this is exported, but the 
great bulk is used for domestic purposes and manufactures, 
-—for animating the giant arm of the steam-engine, and for 
sending our steam-ships over every region of the globe. 
The present aspect of the county was next alluded to, — its 
division into three alluvial valleys, watered by three rivers 
which flow into the estuary of the Firth, — the Pentland 
range of hills, their diversified scenery, — and the remarkable 
basaltic rocks surrounding and forming the basis on which 
the city is built. There are no means of knowing what was 
the condition of the local atmosphere of Mid-Lothian in 
former times — at periods when the country was more densely 
covered with wood, when the ancient forests of Scotland 
still remained, when the surface of the soil was only par- 
tially cleared and cultivated, and imperfectly drained, and 
when marshes and lochs were greatly more abundant than 
they are at present. In the absence of actual facts, people 
are apt to draw on their imaginations and feelings ; and 
it depends a good deal on the individual temperament 
whether we hear that the seasons are become much more 
severe and ungenial, or warmer and drier, than they were in 
bygone days. It was only towards the end of last century 
that scientific instruments were employed to indicate the 
climate of the country. From those begun by Professor 
Playfair in 1771, and others, continued down to the present 
day, it appears pretty evident that no change of climate has 
taken place during the last ninety years. Considerable 
varieties of seasons occur ; the general or normal was pointed 
out, and the occasional or abnormal, with their distinctive 
peculiarities, and the great leading or general causes of dif- 
ference, traced to the predominating power of the south- 
west and north-east air currents, — the predominance of one 
or the other forming the main cause of the varietiea of sea- 
sons, — and to the influence of the great Gulf Stream, which 
flows past the British Isles. Local ameliorations of climate 
by drainage, cultivation of the soil, protection of plantings, 
&c., while they are of the greatest importance to the agri- 
culturist and in a sanitary point of view, would appear to 
be too small to affect the general climatal averages. The 
