Rodolfo Amedeo Lanciani.

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nection while thej are brought toward one another. Let their
positions in the pile be pars£el, with narrow spaces intervening.
For simplicity, let the thickness of each metal plate and interven-
ing space be D. Hie whole work done will be

2Xl(r'0XNg.

The whole mass of the pile (if we neglect that of one of the end
plates) is NAD^, where 9 denotes the mean of the densities of zinc
and copper. Hence, if A be the height to which the whole mass
must be raised against a constant force equal to its weight at the
earth's surface, to do the same amount of work, we have

NAIVA=:2X10-»0XNp;

2X10"* •
which gives A=i =- — ,

or, as ^=8, nearly enough for the present rough estimate,

1



A=



(200000D)a



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260 Scientific Intelligence.

HencG if I>=2nniWiT centimeter,

nence, ii ^_^ centimeter.

The amount of energy thns calculated is not so great as to afford
any argument against the conclusion which general knowledge of
divisibility, electric conductiyity, and other properties of matter
indicates as probable ; that, down to thicknesses of T^jVinr o^ &
centimeter for the metal plates and intervening spaces, the contact
electrification, and the attraction due to it, follow with bat little if
any sensible deviation the laws proved by experiment for plates of
measurable thickness with measurable intervals between them.
But let D be a two-hundred-millionth of a centimeter. If the pre-
ceding formuke were applicable to plates and spaces of this degree
of thinness we should have

A=1,000,000 centimeters or 10 kilometers.
The thermal equivalent of the work thus represented is about 248
times the quantity of heat required to warm the whole mass (con^
posed of equal masses of zinc and copper) by 1^ Cent. This is
probably much more than the whole heat of combination of equal
masses of zinc and copper melted together. For it is not probable
that the compound metal when dissolved in an acid would show
anything approaching to so great a deficiency in the heat evolved
below that evolved when the metallic constituents are separately
dissolved, and their solutions mixed ; but the experiment should
be made. Without any such experiment, however, we may safely
say that the fourfold amount of energy indicated by the preceding
formula, for a value of D yet twice as small, is very much greater
than any estimate which our present knowledge allows us to accept
for the heat of combination of zinc and copper. For something
much less than the thermal equivalent of that amount of energy
would melt the zinc and copper; and, therefore, if in combining
they generated by their mutual attraction any such amount of
energy, a mixture of zinc and copper filings would rush into com-
bination (as the ingredients of gunpowder do) on being heated
enough in any small part of the whole mass to melt together there.
Hence, we may infer that the electric attraction between metalli-
cally-connected plates of zinc and copper of only yxr^nr iooao cf a
centimeter thickness, at a distance of only TTnnrWrnnr ^^ * centi-
meter asunder, must be greatly less than that calculated from the
magnitude of the force and the law of its variation observed for
places of measurable thickness, at measurable distances astmder.
In other words, plates of zinc and copper so thin as a four-hundred-
mUlionth of a centimeter from one another, form a mixture closely
approaching to a molecular combination, if^ indeed, plates so thin
could be made without splitting atoms. Wishing to avoid com-
plication, I have avoided hitherto noticing one important question
as to the energy concerned in the electric attraction of metallically-
connected plates of zinc and copper. Is there not a change of
temnerature in molecularly thin strata of the two metals adjoining
to tne opposed surfaces, when they are allowed to approach one
another, analogous to the heat produced by the condensation of a



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Chemistry and Physics^ 261

gas, the changes of temperature produced by the application of
stresses to elastic solids which you have investigated experiment-
ally, and the cooling effect I have proved to be produced oy draw-
ing out a liquid film which I shall have to notice particularly
below? Easy enough experiments on the contact electricity of
metals will answer this question. If the contact-difference dimin-
ishes as the temperature is raised, it will follow from the Second
Law of Thermodynamics, by reasoning preciselv corresponding
with that which I applied to the liquid film in my letters to you of
February 2d and February dd, 1858,* that plates of the two metals
kept in metallic communication and allowed to approach one
another will experience an elevation of temperature. But if the
contact-difference increases with temperature, the effect of mutual
approach will be a lowering of temperature. On the former sup-
position, the diminution of intrinsic energy in quantities of zinc
and copper, consequent on mutual approach with temperature kept
constant, wiU be greater, and on the latter supposition less, than I
have estimated above. Till the requisite experiments are made,
further speculation on this subject is profitless ; but whatever be
the result, it cannot invalidate the conclusion that a stratum of
^,^^^1^,,^ of a centimeter thick cannot contain in its thickness
many, if so much as one, molecular constituent of the mass. Be-
sides the two reasons for limiting the smallness of atoms or mole-
cules which I have now stated, two others are afforded by the
theory of capillary attraction, and Clausius' and Maxwell's mag-
nificent working out of the Kinetic Theory of gases. In my letters
to you already referred to, I showed that the dynamic value of the
heat required to prevent a bubble from cooling when stretched is
rather more than half the work spent in stretching it Hence, if
we calculate the work required to stretch it to any stated extent,
and multiply the result by J, we have an estimate, near enough
for my present purpose, of the augmentation of energy experienced
by a liquid film when stretched and kept at a constant tempera-
ture. Taking '08 of a gram weight per centimeter of breadth as
the capillary tension of a surface of water, and therefore '16 as
that of a water bubble, I calculate (as you may verify easily) that
a quantity of water extended to a thinness of jTTTimv ^**^ cen-
timeter would, if its tension remained constant, have more energy
than the same mass of water in ordinary condition by about 1,100
times as much as suffices to warm it by 1° Cent This is more
than enough (as Maxwell suggested to me) to drive the liquid into
vapor. Hence, if a film of ^^y^i^^y^ of a centimeter thick can ex-
ist as liquid at all, it \% perfectly certain that there cannot be many
molecules in its thickness. The argument from the Kinetic Theory
of gases leads me to quite a similar conclusion.

5, Comparison of Mechanical JEquivalents: by Pliny Earle
Chase, (Proc. Anu PhiL Soc, xi, 313, 1870). — The comparison
of different mechanical equivalents will open a new field for inves-
tigation, which may prove to be fertile m valuable results. For
* Prooeedings of the BotsI Society for April, 186S.



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282 Sdevktific IntdUgence.

example, recent determinatioiis, by the different methodfl of lliom-
sen and Farmer, fix the mechanical equivalent of light, in a wax
candle burning 126^ grains per hour, at 13*1 foot-pounds per min-
ute, the equivalent of 1 erain being 6*218 foot-pounds. According
to Dulongr, the heat evolved during the combustion of 1 erain of
olive oil in oxygen, is sufficient to heat 9862 grains of water
1^ 0. According to Favre and Silbermann, 1 grain of oil of tur-
pentine, burned in oxygen, would heat 10,852 grains of water
1*^0.

It may therefore be presumed that the total heat ^iven out by
the combustion of 1 grain of wax, is about sufficient to raise
10,000 grains or water 1** C, or 18,000 gr. 1** F. This represents
a mecli^nical e<|uivalence of (18,000 X 772-4- 7000 = ) 1986*143
foot-pounds, which is 319*5 times as great as the corresponding
equivalent of the light given out during the combustioa

Tyndall, in his lecture on Radiation, states that the visible rays
of the electric li^ht contain about one-tenth of the total radiated
heat The relative luminous intensity of an electric lamp would
therefore appear to be about 32 times as great as that of the wax
candle. This ratio so nearly resembles that of solar to terrestrial
superficial att]:action, and the connection of electric and magnetic
currents with solar radiation is so evident, that additional experi-
ments, to furnish materials for a great variety of similar compari-
sons, seem desirable. While it is possible tnat the resemblance,
in the present instance, may be accidental, the numerous harmo-
nies between the manifeBtations of cosmical and molecular forces
render it at least equally possible that it may have a weighty sig-
nificance.

XL GEOLOGY AND MINERALOGY.

\. On a JFbssU Tooth from Table Mountain; by Prof. Wil-
UAM p. Blake. (Communicated by the author for this Journal) —
The fossil tooth, found by Mr. D. T. Hughes, 1,700 feet under
Table Mountain, and 300 feet below the surface, I have carefullv
examined and compared with specimens in the Smithsonian Insti-
tution. It proves to be a back lower molar of an equine animal of
the genus Hippariony or a closely allied ^nus. This genus is
one of the connecting links between the IPaloBotfierium and the
horse.

The specimen closely resembles a fossil in the Smithsonian mu-
seum, from the Pliocene formations of the Niobrara river in Ne-
braska,* not only in size but in the foldings of the enamel, and
particularly in the posterior ])art of the tooth, but it differs enough,
m several particulars, to justify the belief that it is a distinct spe-
cies. Dr. Leidy does not attempt to determine, specifically, uie
specimen from Nebraska, but considers it closely related to, if not
identical specifically with, Hipparion gratumy possibly JhrotoJiip-
puspktcidus.

* Described by Prof. Leidj in his work upon the Extinct Mainin>ili>n Ftuna of
that region, p. 319, pL xix, flg". 7,



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Oeciogy and MiMralogy. 26&

The size of the Table Monntain specimen, which is considerably-
worn by attrition in the eravel, is: length, 11 lines; breadth upon
the crown, 9 lines; breadth at the base, 10 lines; thickness, ante-
riorly, 4 lines, posteriorly, 2 lines.

This fossil is the first of the kind discovered west of the
Rocky Mountains. It adds to the list of the fauna of the period
antedating Table Mountain— hi list which includes the mammoth
{EUphxtSy from Ejiight's Ferry), the rhinoceros, and an animal
allied to the elk. I have believed that remains of man were also
found under the lava ; but upon this point, after diligent inquiry,
I am satisfied that the evidence is insufilcient. But we now add
this fossil allied to Stpparion, and I regard it as another indica-
tion that the Table Mountain beds are Pliocene, and homotaxial
with those of the Bad Lands of Nebraska

2. Cause of the De$eent of Glaciers, — Rev. Hsnbt Mosbley,
before the Royal Society in January, 1869,. in the Philosophical
Magazine for the May following, and at the meeting of the Koyal
Institution of Great Britain, May 13, 1870, opposes the view that
glaciers owe their movement mainly to gravity, and gives as the
principal cause contraction and expansion due to change of temper-
ature through the mass. He compares the movement to that of a
sheet of lead on a sloping surface, in its expansion the lower edge
working downward, and m its contraction uie upper edge or part.

In the PhiL Mag. for July, 1870, Mr. John Ball, after alluding
to the criticisms on the above theory by Mr. Wdl Mathews in
the Alpine Journal for February last, shows that the supposed
contraction and expansion to wmch Canon Moseley i^peals, does
not take place, and that the '' crawling theory " of glacier motion
is therefore unsatisfactory. He argues that the ghicier is not a
continuous solid mass like a sheet of metal ; that the temperature
of the interior, as observers have proved, is very nearly constant ;
that the movement is half as fast in winter as in summer ; that the
rate of motion is not proportioned at all to the length of the gla-
cier as it should be oy the theory ; that the supposed expansion
and contraction, if a fact, would exceed twenty or more times the
rate of actual motion but for modifying causes, — and this is an
amount of modifying intervention for the sake of the theory, suffi-
cient to prove the theory of no value. He concludes as follows :

^^ If I might presume to estimate the net results of this renewed
discussion of the causes of glader-motion, I should say that they
are not considerable, but yet are far from worthless. Canon Mose-
ley's experiments have added something to our knowledge, and
especiiJly those on the tenacity of ice, which have some bearing
on the origin of crevasses. Of far greater importance are the
observations on ice-planks made by Mr. William Mathews. The
first of these, published in the ^ Alpine Journal,' gave prominence
to a fact whicn had long been familiar to myself, and probably to
many others. I have often found that long icicles placed in an
inclined position, and supported only at the upper end, will grad-
ually resume the vertical direction, and I had, perhaps too ligntly,
assumed that this was a particular instance of the process by



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264 * Scient^c InteUtgence.

which ice changes its form through fracture and regelation. In
Mr. Mathew's nrst experiment, conducted during a thaw, a thick
plank of ice supported at each end was deflected at the middle
through a space of 7 inches in as many hours. Although none
hut very mmute fissures were observed, the facts did not seem to
me altogether inconsistent with that explanation. In the second
series of observations, made during the severe frost of February
last, Mr. Mathews found that at temperatures notably below the
freezing-point a plank of ice, supportea as before, subsides slowly
between the pomts of support under the sole influence of its own
weight. The deflection under these circumstances was about 1^
inch in twenty-four hours. Taking this observation in connection
with a multitude of facts recently brought to light, and especially
the researches of M. Tresca, we are led to admit that ice, in cohf
mon with very many apparently rigid bodies, does possess a cer-
tain degree of plasticity which is exhibited bv changes of form
effected very slowly under the action of forces of moderate amount,
rather than bj the rapid action of more powerful agencies.*

^^ The admission of this conclusion may slightly modify, bat
will not materially alter, the views now generaUy held as to the
causes of glacier-motion, which are mainly derived from the remark-
able researches of Professor Tyndall. Whatever may be the final
judgment of men of science, I feel quite sure that it will not con-
firm the opinion expressed by Canon Moseley in his latest publica-
tion: that ^Uhe pnenoraena of glacier-motion belong rather to
mechanical philosophy than to physics." Every real advance that
has been made toward the explanation of those phenomena has
been due to the application of increased knowledge of the physical
properties of glacier-ice ; and if any thing be wanting to complete
the explanation now generally accepted, it must be derived m>m
such additional acquaintance with those properties as may be de-
rived from continued observation and experiment*'

3. The North American LcJcea considered as Chronofneters of
Post-glacial time; by Dr. Edmund Andrews. 24 pp. roy. 8vo.
(Trans. Acad. Sci. Chicago, vol ii). — ^Dr. Andrews oiscusses in
this paper the nature of the post-glacial deposits on the shores of
Lake Michigan, especially in uie vicinity of Chicago, their extent,
the areas of the several beaches, the erosion these beaches have
undergone, the width of the subaqueous plateau formed along the
border of the lake out of the material removed in the erosion, and
the amount of sand moved in the process; and from the elements
thus obtained, arrives at the following conclusions :

(1.) The upper beach began to form immediately after the
Boulder Drift period, and continued to accrete for about 900 years.
No animal fossils have yet been found in it.

(2.) The waters then fell suddenly to about their present level,
where they remained till a thin bed of peat accreted on the marshy
slope vacated by the waves. I have not been able to collect data
for a calculation of this first low-water period, but from the posir

* In Dana^s Manual of Gkology, p. 673, this plasticity is recognized among the
means of motion on the ground of obseryationsi similur to the above, made bj
Kane in his "Arctic Bxplorations." '



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Geology and Mineralogy. 266

tion of the soil-bed in the eastern dunes, I incline to think it lasted
500 or 1000 years.

(3.) The water rose again, submergins for a short time the upper
beach, but soon fell to the line of the middle one, where it remained
about 1,600 or 2000 years. This period appears to be cotemporary
with the Loess.

(4.) The water, which had already slowly fallen some feet, now
retired more rapidly to near its present level, which it has main-
tained with only moderate fluctuations ever since.

(5.) The total time of all these deposits appears to be some-
where between 6,300 and 7,600 years.

The discussion is an interesting and important one. Some un-
certainties in the calculations occur to us ; but without a special
examination of the region we are not at present prepared to men-
tion any but the following. The author writes as it he supposed
that sand in the course of transportation alwavs remained sand.
He observes that ^' the sand movement in the lake is confined to
the shore line," as proved by the fact that " there is no sand in
deep water," not recognizing the well-known geological fact that
sands on coasts are always undergoing wear through the attrition
of grain upon grain under the action of waves and currents, and
that while the finer material made by this attrition is floated off
to deeper waters, the coarser is left behind in such cases near or on
the shores.

3. FossUa in the Mineral veins of the Carboniferous Lime-
stone of Cheat Britain. — A paper on this subject by Mr. Chables
"Moore, (Rep. Brit. Assoc, for 1869, p. 360), contains notices of
numerous fossils in the Lead mines of the Carbonii'erous limestone.
Li the walls of the Charterhouse Lead-mine, in the Mendip range,
270 feet from the surface, over 80 species of Liassic fossils were
obtained by him, and more than 30 of Carboniferous. The Liassic
included a Chara, wood in the form of jet, Rhizopods, Pentacrinites,
a Cidaris and other Echinoderms, Serpula, claws of Crustacea,
many MoUusks, remains of about 10 species of fishes of the
genera AcroduSy Hyhodus^ XepidotuSy &c,, and a tooth of an
Ichthyosaur ; and among the Carboniferous, there were species of
Helix, Hydrobia, Planorbis, Proserpina, Valvata, Vertigo, all
either land or freshwater Mollusks, also 1 1 species of Ostracoids,
besides Mollusks, Serpulse, Encrinites, Corals and Conodonts. A
similar range of facts was observed in connection with other lead
mines. We cite the following general remarks.

Whilst the various mines and mineral deposits I have examined
have certain species in common, it may be said that they have
each special paleontological features of their own.

Li the Keld-Head Mines organic remains are very abundant at
about 460 feet from the surface, amongst which are many Fora-
minifera, chiefly of the genus Involutina^ of which there are six
species, and univalves of about twelve genera, the freshwater
species Yalvata anomcUa Moore^ and Planorbis Mendipensis

Am. Joub. Sol— Second SsiuESt Vol. L, No. 149.— Sept., 1870,
17



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266 Scientific Intelligence,

Moore, being present, and also Entomostraca of several new
species.

The Fallowfield mines, although not yielding a very long list of
species, have their special interest in the presence of the land and
freshwater genera StooBtoma ?, Hydrobia^ and JPisidium ; Invoht-
tina^ as in the Keld-Head mines, though rarely ; and a single seed
of the Flemingites gracilis Carr. The richest samples from this
mine are at 90 and 450 feet from the surface.

The Grassington mines are not only very rich in individual
specimens, but have yielded the greatest number of species,
among which are again freshwater remains of Hydrobiay Ptor
norbis, Valvata^ and Lithoglyphtts, Entomostraca of at least
ten species, Conodonts of several varieties, and fish-remains of the
genera Petalodus, Orodus, Ac.

The Alston mines have yielded about twelve species of uni-
valves, though they are not in good condition. Foraminifera are
presen t, b ut are rare, and fish-remains of the genera PetcUodus,

The Weardale mines, and those of Allenheads, are comparatively
not rich, the vein stuff in them being much mineralized. Cono-
donts occur in the former, Entomostraca rather abundantly in the
latter, and also, though rarely, the genus Hydrobia. In these
veins, and also at Alston, I have detected, for the first time, large
cells of a foraminiferous shell, for which Mr. Brady suggests the
generic name Carteria,

In the White and Silver Band mines remains are somewhat
rarely distributed, the richest deposit being a friable ochreons
sandstone, on the " sun" side of the Silver Band Old Mine, which
yielded many specimens of Hydrobia^ and one or two of Vol-
vata anomam, several genera of Foraminifera, including Invo-
lutina and Dentcdinay with Conodonts, and portions of teeth of
JPsammodus,

The Mount-Pleasant mines of Mold contain Foraminifera, and
also the freshwater Hydrobia^ though rarely, and Conodonts
rather abundantly; but they are especially remarkable for the
great variety of nsh-remains they yield, which appear to i^epresent
at least ten different genera. Mixed with the " dowks" of the
mine are occasionally small pieces of laminated stone the surfaces
of which exhibit numerous traces of fish-scales.

The researches I have been making have involved very consider-
able lal)or and minute investigation; but as they will to some
extent have opened up a new field of inquiry, I nope they will
not be without some results. Before concluding, I desire to refer
to several of the more interesting paleontological facts which
have been obtained. ♦***♦«

Not the least important fact in my mine explorations has been
the discovery of a land and freshwater fauna. Until I obtained
the three genera of Helix^ Vertigo^ and JProserpinu^ with the
freshwater genera Planorbis and Valvatay in tiie Charterhouse
Mine, the only known terrestrial shell below the secondary beds
was the JPupa vestu&ta Daws., found by Sir Charles Lyell and Dr.



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Otology and Mineralogy, 267

DawBon in the Coal measures of Nova Scotda. To the above
genera I have now to add those of Hydrobia^ Stoastoma /,
IdithoglyphuSy and Plsidium^ from the mines of the north of
England, some of which I have little doubt are older than the
Ihipa vetusta of the coal-beds. There is thus the fact of the
presence of nine genera of land and freshwater shells in the lead-
veins of this country.

In addition to the list of organic remains which follows, num-
bering about 112 species from the north of England and North-
Wales mines, eight, which are not in common, have been obtained
from Weston, and to these again are to be added 89 in the list
previously given from Charterhouse, so that in true and workable
mineral veins I have found 209 species. In the Carboniferous
Limestone of the Frome district precisely similar phenomena occur,
though the fissures are not worked. These Rhsetic and Liassic
veins have yielded me about 70 species, so that, including the
districts I have enumerated, I have obtained from vein-fissures,
with their deposits of different ages, about 279 species of organic
remains.

Under these peculiar circumstances, I hkve discovered the oldest
known Mammalia, the oldest land and freshwater MoUusca, about
52 species of fish, and about 8 of Reptilia, besides the other groups
to ^ich reference has been made.

With regard to the origin of the veins, Mr. Moore observes as
follows:

The chief material of all the mineral veins I find to be of marine
origin ; all the organic contents are fossil, and their precise geolo-
gical age can be arrived at without much difficulty. Wherever



Online LibraryRodolfo Amedeo LancianiThe American journal of science and arts → online text (page 83 of 109)