334 Scientific Intelligence. 
as it is now doing, the duration of those seams will not reach half that 
period. How the case may stand in other coal-mining districts I have © 
not the means of ascertaining; but as the best and most accessible coal 
will always be worked in preference to any other, I fear the same rapid 
exhaustion of our most valuable seams is everywhere taking place. Were 
we reaping the full advantage of all the coal we burnt, no objection could 
be made to the largeness of the quantity, but we are using it wastefully 
and extravagantly in all its applications. It is probable that fully one- 
fourth of the entire quantity of coal raised from our mines is used in the 
- production of heat for motive power; but, much as we are in the habit of 
admiring the powers of the steam-engine, our present knowledge of the 
mechanical energy of heat shows that we realise in that engine only a 
small part of the thermic effect of the fuel. That a pound of coal should, 
in our best engines, produce an effect equal to raising a weight of a million 
pounds a foot high, is a result which bears the character of the marvellous, 
and seems to defy all further improvement. Yet the investigations of 
recent years have demonstrated the fact that the mechanical energy resi- 
dent in a pound of coal, and liberated by its combustion, is capable of 
raising to the same height ten times that weight. But although the power 
of our most economical steam-engines has reached, or perhaps somewhat 
exceeded, the limit of a million pounds raised a foot high per lb. of coal, 
yet, if we take the average effect obtained from steam-engines of the various 
constructions now in use, we shall not be justified in assuming it at more 
than one-third of that amount. It follows, therefore, that the average 
quantity of coal which we expend in realising a given effect by means of 
the steam-engine is about thirty times greater than would be requisite 
with an absolutely perfect heat-engine. 
Bones in Drift.—Sir Charles Lyell, in his last work, suggests that 
parts of the north of Europe had a climate of intense cold at the time of 
the supposed co-existence of several extinct quadrupeds with man (the 
maker of the much-discussed flint implements found in the valley of the 
Somme and elsewhere). Presuming that to have been the case, may not 
the same circumstances have prevailed as now occur in Siberia, where 
numerous extinct animals are perfectly preserved in the stratum of ice 
which covers parts of that country, and which probably, with its contents, 
is aremnant of our tertiary period? This ancient stratum of ice is in 
summer undergoing a constant process of destruction by thawing; and 
thus the animals imbedded in it are liberated, and their fleshy parts de- 
caying, the bones remain on the surface of the land, or fall to the bottom 
of the river channels, and, with gravel and mud, must necessarily become 
so mixed up with the remains of man and of his works, as well as with 
the bones of other animals now living in that country, that it would, I 
believe, be impossible for the most skilful observer, after the disappear- 
ance of the ice, to declare, either from their state of preservation or from 
their relative position, that they were not the remains of man and qua- 
drupeds which must have been contemporaneous inhabitants of the land, 
—leading to the same fallacies which may be observed in some of the con- 
clusions which have of late been too hastily drawn regarding the human 
remains found in the drift in connection with those of animals, the species 
of which were probably extinct long before the appearance of man upon 
the scene.—Atheneum. 
Illuminating power of the Electric Light.—The following is a short 
notice of Observations made by Professor W. B. Rogers on the Illu- 
minating Power of one of the large batteries used by Mr Ritchie of 
Boston, United States, in the recent grand exhibitions of the Electric 
Light in that city :—‘ The battery in question, consisting of 250 Bunsen 
