BRITISH ASSOCIATION MEETING. 
427 
BRITISH ASSOCIATION MEETING. 
The British Association Meeting was held this year at Manchester, and was 
marked by an unusually large attendance of members and associates. 
The President's Address. 
The President, Mr. Pairbairn, in his opening address, dwelt but slightly on 
the progress of Geology — the chief portion of his speech being devoted, as 
was to be expected, to manufactures and applied mechanics. We give that 
part of his speech which relates to our science. 
" It is little more than half a century since Geology assumed the distinctive 
character of a science. Taking into consideration the aspects of nature in 
different epochs of the history of the earth, it has been found that the study 
of the changes at present going on in the world around us enable us to under- 
stand the past revolutions of the globe, and the conditions and circumstances 
under which strata have been formed and organic remains embedded and pre- 
served. The geologist has increasingly tended to believe that the changes 
which have taken place on the face of the globe, from the earliest times to the 
present, are the result of agencies still at work. But whilst it is his high 
office to record the distribution of life in past ages and the evidence of physical 
changes in the arrangement of land and water, his results hitherto have indi- 
cated no traces of its beginning, nor have they afforded evidence of the time 
of its future duration. Geology has been indebted for this progress very largely 
to the investigations of Sedgwick and the writings of Sir Charles Lyell. 
" As an example of the application of Geology to the practical uses of life, I 
may cite the discovery of the gold fields of Australia, which might long have 
remained hidden, but for the researches of Sir Roderick Murchison in the 
Ural Mountains on the geological position of the strata from which the Russian 
gold is obtained. Prom this investigation he was led by inductive reasoning 
to believe that gold would be found in similar rocks, specimens of which had 
: been sent him from Australia. The last years of the active life of this dis- 
, tinguished geologist have been devoted to the re-examination of the'^rocks of 
his native Highlands of Scotland. Applying to them those principles .of classi- 
I fication which he long since established, he has demonstrated that the crystal- 
line limestones and quartz-rocks which are associated with mica-schists, &c., 
belong by their embedded organic remains to the Lower Silurian Rocks. 
Descending from this well-marked horizon, he shows the existence beneath all 
such fossiliferous strata of vast masses of sandstone and conglomerate of 
Cambrian age; and, lastly, he has proved the existence of a fundamental 
Gneiss, on which all the other rocks repose, and which, occupying the North- 
western Hebrides and the west coasts of Sutherland and Ross, is the oldest 
rock-formation in the British Isles, it being unknown in England, Wales, or 
Ireland. 
" It is well known that the temperature increases, as we descend through the 
earth's crust, from a certain point near the surface, at which the temperature 
is constant. In various mines, borings, and Artesian wells, the temperature 
has been found to increase about 1° Fahrenheit for every sixty or sixty-five feet 
of descent. In some carefully conducted experiments during the sinking of the 
Dukinfield Deep Mine, — one of the deepest pits in this country, — it was found 
that a mean increase of about 1° in seventy-one feet occurred. If we take 
the ratio thus indicated, and assume it to extend to much greater depths, we 
should reach at two and a half miles from the surface strata at the temperature 
of boiling water ; and at depths of about fifty or sixty miles the temperature 
