1864. | Geology and Paleontology. 119 
parison with those of gunpowder, and the far inferior heat imparted to 
the gun itself, it will be seen that the advantages attending the employ- 
ment of gun-cotton, are so many and so important as to call impera- 
tively for the fullest investigation. 
From gun-cotton to armour-plated ships is a natural transition in 
these warlike days. Science seems to be at fault on the subject of the 
preservation of iron plates from oxidation and fouling. One of the 
best processes, that has yet come under our notice, is due to Messrs. 
Johnson and Calvert. They propose to coat the iron with a thin layer 
of metallic zinc, as in the ordinary process of galvanizing. Their 
results prove that the film of zinc exercises a great protective power 
against the corrosive action of sea-water; upwards of a year’s ex- 
posure showing that four or five times as much corrosion took place in 
the case of uncoated as with galvanized iron plates. Whether galva- 
nizing would prevent fouling, remains to be seen; we suspect it would 
rather aggravate this evil. 
V. GEOLOGY AND PALZONTOLOGY. 
TueERE is perhaps more difficulty in describing the periodical progress 
of Geology, than there is in recording that of any other science. 
The exactitude of the advance is less decided, the views set forth more 
speculative, and the facts given more open to objection or discussion, 
than is the case in any other department of intellectual investigation. 
In Chemistry, the discovery of an element or of some previously un- 
known compound, gives a fixed and tangible point from which to go 
onward to further knowledge. Every step is a permanent score in the 
continuous tally. So the discovery of a comet or a planet, or a nebula, 
or more exact measurements of angles, or of distances, or the detection 
of errors of observation, or calculations or the revelations of increased 
telescopic powers, all’ yield for Astronomy definite and incontrovertible 
results, and it is only in the special sphere of absolutely speculative 
Astronomy, that there is any uncertainty whatever. So, too, in Botany, 
a new flower, or a flora of some previously unnoticed region, is 
so much substantially added to the previous knowledge, so much gain 
which can be appreciated and recorded. But in Geology, we have to 
deal with the rags and shreds of former ages and former beings, 
nothing whole or entire,—every relic has to be dug out of the débris 
and ruins, which we have, as it were, first to clear away before we can 
get a glimpse of any treasures remaining beneath, and when we find 
these they are damaged and mostly broken fragments which we have 
to join and fit, and put together, to get, in the best way we can, some 
general notion of what they originally were. Thus it is a new geo- 
logical idea gets started, and is discussed, opposed, supported, until 
finally substantiated or disproved; in short, it is only after a contest 
_ that, generally speaking, any progress in this science is admitted. In 
