1876.] 
The British Association 
to realise the mathematical conception that, “ if electricity is to convey all the 
delicacies of quality which distinguish articulate speech, the strength of its 
current must vary continuously and as nearly as may be in simple proportion 
to the velocity of a particle of air engaged in constituting the sound ?” 
The Patent Museum of Washington, an institution of which the nation 
was justly proud, and the beneficent working of the United States patent 
laws, deserved notice. He was much struck with the prevalence of patented 
inventions in the Philadelphia Exhibition. He asked one inventor of a very 
good invention “why don’t you patent it in England?” The answer was 
“ The conditions in England are too onerous.” We certainly were far behind 
America’s wisdom in this respedt. If Europe did not amend its patent laws 
(England in the opposite direction to that proposed in the bills before the last 
two sessions of Parliament) America would speedily become the nursery of 
useful inventions for the world. Pie might also mention “ Old Prob’s ” 
weather warnings, which cost the nation 250,000 dollars a year; and though 
Democrats or Republicans playing the “ economical ticket ” might for half a 
session stop the appropriations for even the United States Coast Survey, no 
one would for a moment think of starving “ Old Prob.” The United States’ 
Naval Observatory was full of the very highest science under the command of 
Admiral Davis. If to get on to precession and nutation, he had resolved to 
omit saying that he had there, in an instrument for measuring photographs of 
the Transit of Venus seen, for the first time in an astronomical instrument, a 
geometrical slide, the verdiCt on the disaster on board the Thunderer, pub- 
lished while writing his address, forbade him to keep any such resolution, and 
compelled him to put the question, “ Is there in the British Navy, or in a 
British steamer, or in a British land boiler another safety-valve so constructed 
that by any possibility, at any temperature, or under any stress it can jam ?” 
and to say that if there was it must be instantly corrected or removed. 
Passing to the subject of his address, Sir William Thomson said that the 
evidence of a high internal temperature was too well known to need any 
quotation of particulars at present. Below the uppermost ten metres stratum 
of rock or soil sensibly affeCted by diurnal and annual variations of tempera- 
ture, there was generally found a gradual increase of temperature downwards, 
approximating roughly, in ordinary localities, to an average rate of 1 deg. C. 
per thirty metres of descent, but much greater in the neighbourhood of aCtive 
volcanoes, and certain other special localities of comparatively small area, 
where hot springs and perhaps also sulphurous vapours prove an intimate 
relationship to volcanic quality. It was worthy of remark in passing that so 
far as we know at present there were no localities of exceptionally small rate 
of augmentation of underground temperature, and none where temperature 
diminishes at any time through any considerable depth downwards below the 
stratum sensibly influenced by summer heat and winter cold. By a simple 
effort of geological calculus it had been estimated that 1 deg. per 30 metres 
gives 1000 deg. per 30 kilometres, and 3333 deg. per 100 kilometres. This 
arithmetical result was irrefragable, but what of the physical conclusion drawn 
from it with marvellous frequency and pertinacity that at depths of from 30 
to 100 kilometres the temperatures are so high as to melt all substances com- 
posing the earth’s upper crust ? It had been remarked, indeed, that “ if observa- 
tion showed any diminution or augmentation of the rate of increase of under- 
ground temperature in great depths, it would not be right to reckon on the 
uniform rate of 1 deg. per 30 metres, or thereabouts, down to 30, or 60, or 100 
kilometres. But observation has shown nothing of the kind, and, therefore, 
surely it is most consonant with inductive philosophy to admit no great devia- 
tion in any part of the earth’s solid crust from the rate of increase proved by 
observation as far as the greatest depths to which we have reached.” Now he 
had to remark upon this that the greatest depths to which we have reached in 
observations of underground temperature was scarcely one kilometre ; and 
that if any falling offof the rate of augmentation of underground temperature 
was sensible at a depth of one kilometre, this would demonstrate that within 
the last 10,000 years the upper surface of the earth must have been at a 
higher temperature than that now found at the depth of one kilometre. 
