March 23, 1882] 
NATURE 
485 
secuting his anatomical studies, as are shown by his 
further observations on the heart, among which he gives 
the results of his experiments on the heart of a dog; by 
his memoirs on the muscles of eagles; on the intestinal 
movements in cats; and on the bile ducts, &c. 
Three years after the publication of these treatises on 
special points, he brought out his ‘ Elements of Myo- 
logy,” in which he treated the subject more from a 
mechanical than an anatomical point of view. In a 
letter to Thevenot, published with this work, he gives 
an account of the dissection of a shark which had been 
captured off Leghorn in 1666, and especially discusses 
the character and mode of growth of the teeth of that 
animal. This seems to have been a favourite line of 
inquiry about that time, for next year (1667) Agostino 
Scilla published his work, ‘La Vana Speculazione dis- 
anganata dal senso,’’ in which, with a view of proving 
the organic origin of fossils, he figures and describes 
sharks’ heads and teeth, in order to compare them with 
the glossopietre, or fossil sharks’ teeth, so commonly 
found in the Tertiary beds of Italy. 
It was about this time 1667-9 that Steno extended his 
researches into the field of geology, and began to write a 
dissertation in Italian for the Academia della Crusca, of 
which unfortunately only the introduction has been handed 
down tous. This bears the title “ De Solido intra soli- 
dum Naturaliter Contento Dissertationis Prodromus.”’ 
(Florence, 1669, in 4to.) 
In this work he showed that he held views far in 
advance of his age, at any rate that no one else had 
clearly stated them, for we cannot but feel that in most 
cases of this sort we have got the wisdom of many and 
the wit of one. The independent researches of a number 
of different observers suggest the same explanation, but 
each is afraid to bring it forward on the evidence that he 
alone has gathered. A bold clear-headed generaliser 
steps forward and says, why not accept the conclusions 
that naturally follow from the hypothesis that each of you 
severally feel would best explain the various phenomena | 
you have been investigating ? 
At any rate Steno did give a fair sketch of the Prin- 
ciples of Geology, and showed that he had considered it 
from the petrological, palzeontological, and stratigraphical 
point of view. He pointed out the difference between 
rocks of mechanical origin, and those which were due to 
chemical agencies, and further clearly distinguished those 
that were to be referred to ordinary subaqueous sediment 
from those which were the products of eruption. 
He found it necessary to mention by way of illustration 
what any one would admit as soon as their attention was 
called to it, that if we found a deposit containing sea salt 
and the remains of marine animals, planks of ships, &c., 
we should allow that the sea had once been there, whether 
the bed was exposed in consequence of the sea having 
retired or because the land had been raised. 
A great quantity of timber and things washed down 
from the land suggest transport by torrents and rivers. 
Charcoal, cinders, and calcined objects we refer to the 
action of fire. 
If the strata are of the same kind we infer the same 
causes. But if the character of the deposits which make 
up a set of beds in one and the same place varies, we 
refer this to changes in the surrounding conditions affect- 
ing the flow, or the source from which the material was 
derived from time to time. 
He further shows that although the lowest beds de- 
posited over any area must conform to the shape of the 
underlying rock, the tendency of all sediment must be to 
assume a horizontal position ; and so, when we find them 
highly inclined, we must refer this to subsequent move- 
ment, excepting, of course, in the case of false bedding, 
which probably he would include under his aqueous 
causes of inclination of strata. 
He observes that mountains, often with flat tops, are 
made up of both horizontal and inclined strata, as may 
be seen along their flanks, and from all his observations 
inferred that once the mountains were not, that they do 
not grow, that there is no constant direction in mountain 
chains, and he infers that mountain regions are raised 
and depressed, and subject to rending and fissuring. Dis- 
cussing the origin of springs, he shows that he hada clear 
idea on the subject of Artesian wells, which had been 
previously treated by Ramazzini [De Miranda fontium 
mutinensium scaturigine, £596.] 
As he had clear notions of the structure of the crust 
of the earth and of the origin of the sedimentary rocks, 
we are not surprised to find that he entertained correct 
views respecting the nature of fossils. He pointed out 
that some shells were preserved just as they had been 
left by the sea or lake; others had undergone a slight 
change, the original shell being altered or replaced, while, 
in a third case, the shell had perished and left only the 
cast in the rock. We must remember what queer ideas 
he had to meet when we read of his explanations and 
arguments to prove what seems now so clear; forexample, 
how he dwelt upon the occurrence in the rock of a 
large shell bored by lithodomous mollusks, and had to 
combat the view that they were concretions! Again a 
common idea with regard to the sharks’ teeth of Malta was 
that they were the spontaneous productions of the soil, 
while popular superstition referred them all to the miracle 
by which St. Paul deprived all the snakes in the island of 
their venom. So Steno had to meet the argument derived 
from the great numbers that are there found. He pointed 
out first that each fish has an enormous number of teeth ; 
next that the sea often carries and collects into one place 
bodies of the same kind, sorting them, as we know now, 
according to their size, specific gravity, and so on; and 
thirdly, that these sharks herd together, so that it was 
likely there should be a large number of their teeth in 
one place ; and he adds that as there are teeth of different 
fish as well as shells in the same beds, it was clear that 
we had todo with an ordinary marine deposit. 
He does not seem to have determined the bones of the 
large mammalia or to have studied their mode of occur- 
rence very carefully, for though he recognised elephants, 
he did not see the difficulty that arose from the occur- 
rence of a great number of other large animals, nor did 
he realise in what ancient deposits they were found, and 
so he thought it a sufficient explanation to say that the 
elephants had been brought over by Hannibal. He was 
hampered by the attempt to classify the events of geology 
under six periods, and had rather to wrest his facts to 
make them fit with his explanation of the Noachian 
deluge. 
It is less interesting to dwell upon these difficulties 
than to follow him where he made the great advances ot 
his age, and laid down the simple law of paleontology 
that when we find a body imbedded in the rocks, and it 
is similar in all important points to a recent organism, it 
is a fair inference that it also did belong to such an 
organism, or when he gave as the result of his investiga- 
tions that the deposits of past ages and their included 
remains were produced in just the same way as similar 
accumulations are formed in modern times, and that 
the succession of beds with marine shells such as were 
seen in various parts of Tuscany clearly proved that 
there had been alternate periods of submergence and of 
elevation over large areas. 
In discussing the possible causes of these earth move- 
ments, he touches the question of internal heat, and 
in inguiring into the causes of hot and cold springs, cur- 
rents of air of different temperatures, emanation of gases, 
&c., he speculates upon the effects of the internal heat 
of the earth, and here and there throws out hints of 
larger questions working in his mind, as, for instance, 
modifications of the earth’s crust, such that the centre 
of gravity should no longer so nearly coincide with the 
