Adhémar’s theory has been advocated by M. Le Hon, of Brussels, in a

work entitled _Périodicité des Grands Déluges_. Bruxelles et Leipzig,

1858.

II.

ON THE NATURE OF HEAT-VIBRATIONS.[323]

From the _Philosophical Magazine_ for May, 1864.

In a most interesting paper on “Radiant Heat,” by Professor Tyndall,

read before the Royal Society in March last, it is shown conclusively

that the _period_ of heat-vibrations is not affected by the state

of aggregation of the molecules of the heated body; that is to say,

whether the substance be in the gaseous, the liquid, or, perhaps, the

solid condition, the tendency of its molecules to vibrate according to

a given period remains unchanged. The force of cohesion binding the

molecules together exercises no effect on the rapidity of vibration.

I had arrived at the same conclusion from theoretical considerations

several years ago, and had also deduced some further conclusions

regarding the nature of heat-vibrations, which seem to be in a measure

confirmed by the experimental results of Professor Tyndall. One of

these conclusions was, that the heat-vibration does not consist in

a motion of an aggregate mass of molecules, but in a motion of the

individual molecules themselves. Each molecule, or rather we should

say each atom, acts as if there were no other in existence but

itself. Whether the atom stands by itself as in the gaseous state,

or is bound to other atoms as in the liquid or the solid state, it

behaves in exactly the same manner. The deeper question then suggested

itself, viz., what is the nature of that mysterious motion called heat

assumed by the atom? Does it consist in excursions across centres

of equilibrium external to the atom itself? It is the generally

received opinion among physicists that it does. But I think that the

experimental results arrived at by Professor Tyndall, as well as some

others which will presently be noticed, are entirely hostile to such an

opinion. The relation of an atom to its centre of equilibrium depends

entirely on the state of aggregation. Now if heat-vibrations consist in

excursions to and fro across these centres, then the _period_ ought to

be affected by the state of aggregation. The higher the _tension_ of

the atom in regard to the centre, the more rapid ought its movement to

be. This is the case in regard to the vibrations constituting sound.

The harder a body becomes, or, in other words, the more firmly its

molecules are bound together, the higher is the _pitch_. Two harp-cords

struck with equal force will vibrate with equal force, however much

they may differ in the rapidity of their vibrations. The _vis viva_

of vibration depends upon the force of the stroke; but the rapidity

depends, not on the stroke, but upon the tension of the cord.

That heat-vibrations do not consist in excursions of the molecules

or atoms across centres of equilibrium, follows also as a necessary

consequence from the fact that the real specific heat of a body remains

unchanged under all conditions. All changes in the specific heat of a

body are due to differences in the amount of heat consumed in molecular

work against cohesion or other forces binding the molecules together.

Or, in other words, to produce in a body no other effect than a given

rise of temperature, requires the same amount of force, whatever may be

the physical condition of the body. Whether the body be in the solid,

the fluid, or the gaseous condition, the same rise of temperature

always indicates the same quantity of force consumed in the simple

production of the rise. Now, if heat-vibrations consist in excursions

of the atom to and fro across a centre of equilibrium _external to

itself_, as is generally supposed, then the _real_ specific heat of a

solid body, for example, _ought to decrease with the hardness of the

body_, because an increase in the strength of the force binding the

molecules together would in such a case tend to favour the rise in the

rapidity of the vibrations.

These conclusions not only afford us an insight into the hidden nature

of heat-vibrations, but they also appear to cast some light on the

physical constitution of the atom itself. They seem to lead to the

conclusion that the ultimate atom itself is _essentially elastic_.[324]

For if heat-vibrations do not consist in excursions of the atom, then

it must consist in alternate expansions and contractions of the atom

itself. This again is opposed to the ordinary idea that the atom is

essentially solid and impenetrable. But it favours the modern idea,

that matter consists of forces of resistance acting from a centre.

Professor Tyndall in a memoir read before the Royal Society “On a new

Series of Chemical Reactions produced by Light,” has subsequently

arrived at a similar conclusion in reference to the atomic nature of

heat-vibrations. The following are his views on the subject:—

“A question of extreme importance in molecular physics here

arises:—What is the real mechanism of this absorption, and where is its

seat?

“I figure, as others do, a molecule as a group of atoms, held together

by their mutual forces, but still capable of motion among themselves.

The vapour of the nitrite of amyl is to be regarded as an assemblage

of such molecules. The question now before us is this:—In the act

of absorption, is it the _molecules_ that are effective, or is it

their constituent _atoms?_ Is the _vis viva_ of the intercepted waves

transferred to the molecule as a whole, or to its constituent parts?

“The molecule, as a whole, can only vibrate in virtue of the forces

exerted between it and its neighbour molecules. The intensity of these

forces, and consequently the rate of vibration, would, in this case,

be a function of the distance between the molecules. Now the identical

absorption of the liquid and of the vaporous nitrite of amyl indicates

an identical vibrating period on the part of liquid and vapour, and

this, to my mind, amounts to an experimental demonstration that the

absorption occurs in the main _within_ the molecule. For it can hardly

be supposed, if the absorption were the act of the molecule as a whole,

that it could continue to affect waves of the same period after the

substance had passed from the vaporous to the liquid state.”—_Proc. of

Roy. Soc._, No. 105. 1868.

Professor W. A. Norton, in his memoir on “Molecular Physics,”[325] has

also arrived at results somewhat similar in reference to the nature of

heat-vibrations. “It will be seen,” he says, “that these (Mr. Croll’s)

ideas are in accordance with the conception of the constitution of a

molecule adopted at the beginning of the present memoir (p. 193), and

with the theory of heat-vibrations or heat-pulses deduced therefrom (p.

196).”[326]

III.

ON THE REASON WHY THE DIFFERENCE OF READING BETWEEN A

THERMOMETER EXPOSED TO DIRECT SUNSHINE AND ONE SHADED

DIMINISHES AS WE ASCEND IN THE ATMOSPHERE.[327]

From the _Philosophical Magazine_ for March, 1867.

The remarkable fact was observed by Mr. Glaisher, that the difference

of reading between a black-bulb thermometer exposed to the direct rays

of the sun and one shaded diminishes as we ascend in the atmosphere.

On viewing the matter under the light of Professor Tyndall’s important

discovery regarding the influence of aqueous vapour on radiant heat,

the fact stated by Mr. Glaisher appears to be in perfect harmony with

theory. The following considerations will perhaps make this plain.

The shaded thermometer marks the temperature of the surrounding

air; but the exposed thermometer marks not the temperature of the

air, but that of the bulb heated by the direct rays of the sun. The

temperature of the bulb depends upon two elements: (1) the rate at

which it receives heat by _direct radiation_ from the sun above, the

earth beneath, and all surrounding objects, and by _contact_ with the

air; (2) the rate at which it loses heat by radiation and by contact

with the air. As regards the heat gained and lost by contact with the

surrounding air, both thermometers are under the same conditions,

or nearly so. We therefore require only to consider the element of

radiation.

We begin by comparing the two thermometers at the earth’s surface, and

we find that they differ by a very considerable number of degrees.

We now ascend some miles into the air, and on again comparing the

thermometers we find that the difference between them has greatly

diminished. It has been often proved, by direct observation, that the

intensity of the sun’s rays increases as we rise in the atmosphere.

How then does the exposed thermometer sink more rapidly than the

shaded one as we ascend? The reason is obviously this. The temperature

of the thermometers depends as much upon the rate at which they are

losing their heat as upon the rate at which they are gaining it.

The higher temperature of the exposed thermometer is the result of

_direct radiation_ from the sun. Now, although this thermometer

receives by radiation more heat from the sun at the upper position

than at the lower, it does not necessarily follow on this account

that its temperature ought to be higher. Suppose that at the upper

position it should receive one-fourth more heat from the sun than at

the lower, yet if the rate at which it loses its heat by radiation

into space be, say, one-third greater at the upper position than at

the lower, the temperature of the bulb would sink to a considerable

extent, notwithstanding the extra amount of heat received. Let us now

reflect on how matters stand in this respect in regard to the actual

case under our consideration. When the exposed thermometer is at the

higher position, it receives more heat from the sun than at the lower,

but it receives less from the earth; for a considerable part of the

radiation from the earth is cut off by the screen of aqueous vapour

intervening between the thermometer and the earth. But, on the whole,

it is probable that the total quantity of radiant heat reaching the

thermometer is greater in the higher position than in the lower.

Compare now the two positions in regard to the rate at which the

thermometer loses its heat by radiation. When the thermometer is at the

lower position, it has the warm surface of the ground against which to

radiate its heat downwards. The high temperature of the ground thus

tends to diminish the rate of radiation. Above, there is a screen of

aqueous vapour throwing back upon the thermometer a very considerable

part of the heat which the instrument is radiating upwards. This, of

course, tends greatly to diminish the loss from radiation. But at

the upper position this very screen, which prevented the thermometer

from throwing off its heat into the cold space above, now affects

the instrument in an opposite manner; for the thermometer has now to

radiate its heat downwards, not upon the warm surface of the ground

as before, but upon the cold upper surface of the aqueous screen

intervening between the instrument and the earth. This of course tends

to lower the mercury. We are now in a great measure above the aqueous

screen, with nothing to protect the thermometer from the influence of

cold stellar space. It is true that the air above is at a temperature

little below that of the thermometer itself; but then the air is dry,

and, owing to its diathermancy, it does not absorb the heat radiated

from the thermometer, and consequently the instrument radiates its heat

directly into the cold stellar space above, some hundreds of degrees

below zero, almost the same as it would do were the air entirely

removed. The enormous loss of heat which the thermometer now sustains

causes it to fall in temperature to a great extent. The molecules of

the comparatively dry air at this elevation, being very bad radiators,

do not throw off their heat into space so rapidly as the bulb of the

exposed thermometer; consequently their temperature does not (for this

reason) tend to sink so rapidly as that of the bulb. Hence the shaded

thermometer, which indicates the temperature of those molecules, is

not affected to such an extent as the exposed one. Hence also the

difference of reading between the two instruments must diminish as we

rise in the atmosphere.

This difference between the temperature of the two thermometers

evidently does not go on diminishing to an indefinite extent. Were we

able to continue our ascent in the atmosphere, we should certainly

find that a point would be reached beyond which the difference of

reading would begin to increase, and would continue to do so till the

outer limits of the atmosphere were reached. The difference between

the temperatures of the two thermometers beyond the limits of the

atmosphere would certainly be enormous. The thermometer exposed to

the direct rays of the sun would no doubt be much colder than it had

been when at the earth’s surface; but the shaded thermometer would

now indicate the temperature of space, which, according to Sir John

Herschel and M. Pouillet, is more than 200° Fahrenheit below zero.

It follows also, from what has been stated, that even under direct

sunshine the removal of the earth’s atmosphere would tend to lower the

temperature of the earth’s surface to a great extent. This conclusion

also follows as an immediate inference from the fact that the earth’s

atmosphere, as it exists at present charged with aqueous vapour,

affects terrestrial radiation more than it does radiation from the sun;

for the removal of the atmosphere would increase the rate at which the

earth throws off its heat into space more than it would increase the

rate at which it receives heat from the sun; therefore its temperature

would necessarily fall until the rate of radiation _from_ the earth’s

surface exactly equalled the rate of radiation _to_ the surface. Let

the atmosphere again envelope the earth, and terrestrial radiation

would instantly be diminished; the temperature of the earth’s surface

would therefore necessarily begin to rise, and would continue to do so

till the rate of radiation from the surface would equal the rate of

radiation received by the surface. Equilibrium being thus restored, the

temperature would remain stationary. It is perfectly obvious that if we

envelope the earth with a substance such as our atmosphere, that offers

more resistance to terrestrial radiation than to solar, the temperature

of the earth’s surface must necessarily rise until the heat which is

being radiated off equals that which is being received from the sun.

Remove the air and thus get quit of the resistance, and the temperature

of the surface would fall, because in this case a lower temperature

would maintain equilibrium.

It follows, therefore, that the moon, which has no atmosphere, must

be much colder than our earth, even on the side exposed to the sun.

Were our earth with its atmosphere as it exists at present removed to

the orbit of Venus or Mars, for example, it certainly would not be

habitable, owing to the great change of temperature that would result.

But a change in the physical constitution of the atmospheric envelope

is really all that would be necessary to retain the earth’s surface at

its present temperature in either position.

IV.

REMARKS ON MR. J. Y. BUCHANAN’S THEORY OF THE VERTICAL

DISTRIBUTION OF TEMPERATURE OF THE OCEAN.[328]

Since the foregoing was in type, a paper on the “Vertical Distribution

of Temperature of the Ocean,” by Mr. J. Y. Buchanan, chemist on board

the _Challenger_, has been read before the Royal Society.[329] In that

paper Mr. Buchanan endeavours to account for the great depth of warm

water in the middle of the North Atlantic compared with that at the

equator, without referring it to horizontal circulation of any kind.

The following is the theory as stated by Mr. Buchanan:—

“Let us assume the winter temperature of the surface-water to be 60° F.

and the summer temperature to be 70° F. If we start from midwinter, we

find that, as summer approaches, the surface-water must get gradually

warmer, and that the temperature of the layers below the surface must

decrease at a very rapid rate, until the stratum of winter temperature,

or 60° F., is reached; in the language of the isothermal charts, the

isothermal line for degrees between 70° F. (if we suppose that we have

arrived at midsummer) and 60° F. open out or increase their distance

from each other as the depth increases. Let us now consider the

conditions after the summer heat has begun to waver. During the whole

period of heating, the water, from its increasing temperature, has been

always becoming lighter, so that heat communication by convection with

the water below has been entirely suspended during the whole period.

The heating of the surface-water has, however, had another effect,

besides increasing its volume; it has, by evaporation, rendered it

denser than it was before, at the same temperature. Keeping in view

this double effect of the summer heat upon the surface-water, let us

consider the effect of the winter cold upon it. The superficial water

having assumed the atmospheric temperature of, say 60° F., will sink

through the warmer water below it, until it reaches the stratum of

water having the same temperature as itself. Arrived here, however,

although it has the same temperature as the surrounding water,

the two are no longer in equilibrium, for the water which has come

from the surface, has a greater density than that below at the same

temperature. It will therefore not be arrested at the stratum of the

same temperature, as would have been the case with fresh water; but it

will continue to sink, carrying of course its higher temperature with

it, and distributing it among the lower layers of colder water. At

the end of the winter, therefore, and just before the summer heating

recommences, we shall have at the surface a more or less thick stratum

of water having a nearly uniform temperature of 60° F., and below this

the temperature decreasing at a considerable but less rapid rate than

at the termination of the summer heating. If we distinguish between

_surface-water_, the temperature of which rises with the atmospheric

temperature (following thus, in direction at least, the variation of

the seasons), and _subsurface_-water, or the stratum immediately below

it, we have for the latter the, at first sight, paradoxical effect of

summer cooling and winter heating. The effect of this agency is to

diffuse the same heat to a greater depth in the ocean, the greater the

yearly range of atmospheric temperature at the surface. This effect

is well shown in the chart of isothermals, on a vertical section,

between Madeira and a position in lat. 3° 8′ N., long. 14° 49′ W. The

isothermal line for 45° F. rises from a depth of 740 fathoms at Madeira

to 240 fathoms at the above-mentioned position. In equatorial regions

there is hardly any variation in the surface-temperature of the sea;

consequently we find cold water very close to the surface all along the

line. On referring to the temperature section between the position lat.

3° 8′ N., long. 14° 49′ W., and St. Paul’s Rocks, it will be seen that,

with a surface-temperature of from 75° F. to 79° F., water at 55° F. is

reached at distances of less than 100 fathoms from the surface. Midway

between the Azores and Bermuda, with a surface-temperature of 70° F.,

it is only at a depth of 400 fathoms that we reach water of 55° F.”

What Mr. Buchanan states will explain why the mean annual temperature

of the water at the surface extends to a greater depth in the middle

of the North Atlantic than at the equator. It also explains why the

temperature from the surface downwards decreases more rapidly at the

equator than in the middle of the North Atlantic; but, if I rightly

understand the theory, it does not explain (and this is the point at

issue) why at a given depth the temperature of the water in the North

Atlantic should be higher than the temperature at a corresponding depth

at the equator. Were there no horizontal circulation the greatest

thickness of warm water would certainly be found at the equator and

the least at the poles. The isothermals would in such a case gradually

slope downwards from the poles to the equator. The slope might not be

uniform, but still it would be a continuous downward slope.

V.

ON THE CAUSE OF THE COOLING EFFECT PRODUCED ON SOLIDS BY

TENSION.[330]

From the _Philosophical Magazine_ for May, 1864.

From a series of experiments made by Dr. Joule with his usual accuracy,

he found that when bodies are subjected to tension, a cooling effect

takes place. “The quantity of cold,” he says, “produced by the

application of tension was sensibly equal to the heat evolved by its

removal; and further, that the thermal effects were proportional to

the weight employed.”[331] He found that when a weight was applied to

compress a body, a certain amount of heat was evolved; but the same

weight, if applied to stretch the body, produced a corresponding amount

of cold.

This, although it does not appear to have been remarked, is a most

singular result. If we employ a force to compress a body, and then ask

what has become of the force applied, it is quite a satisfactory answer

to be told that the force is converted into heat, and reappears in the

molecules of the body as such; but if the same force be employed to

stretch the body, it will be no answer to be told that the force is

converted into cold. Cold cannot be the force under another form, for

cold is a privation of force. If a body, for example, is compressed by

a weight, the _vis viva_ of the descending weight is transmitted to the

molecules of the body and reappears under that form of force called

heat; but if the same weight is applied so as to stretch or expand the

body, not only does the force of the weight disappear without producing

heat, but the molecules which receive the force lose part of that

which they already possessed. Not only does the force of the weight

disappear, but along with it a portion of the force previously existing

in the molecules under the form of heat. We have therefore to inquire,

not merely into what becomes of the force imparted by the weight, but

also what becomes of the force in the form of heat which disappears

from the molecules of the body itself. That the _vis viva_ of the

descending weight should disappear without increasing the heat of the

molecules is not so surprising, because it may be transformed into some

other form of force different from that of heat. For it is by no means

evident _à priori_ that heat should be the only form under which it

may exist. But it is somewhat strange that it should cause the force

previously existing in the molecules in the form of heat also to change

into some other form.

When a weight, for example, is employed to stretch a solid body, it

is evident that the force exerted by the weight is consumed in work

against the cohesion of the particles, for the entire force is exerted

so as to pull them separate from each other. But the cooling effect

which takes place shows that more force disappears than simply what

is exerted by the weight; for the cooling effect is caused by the

disappearance of force in the shape of heat from the body itself. The

force exerted by the weight disappears in performing work against the

cohesion of the particles of the body stretched. But what becomes

of the energy in the form of heat which disappears from the body at

the same time? It must be consumed in performing work of some kind

or other. The force exerted by the weight cannot be the cause of the

cooling effect. The transferrence of force from the weight to the body

may be the cause of a heating effect—an increase of force in the body;

but this transferrence of force to the body cannot be the cause of a

decrease of force in the body. If a decrease of force actually follows

the application of tension, the weight can only be the occasion, not

the cause of the decrease.

In what manner, then, does the stretching of the body by the weight

become the occasion of its losing energy in the shape of heat? Or, in

other words, what is the cause of the cooling effects which result

from tension? The probable explanation of the phenomenon seems to

be this: if the molecules of a body are held together by any force,

of whatever nature it may be, which prevents any further separation

taking place, then the entire heat applied to such a body will appear

as temperature; but if this binding force becomes lessened so as to

allow further expansion, then a portion of the heat applied will be

lost in producing expansion. All solids at any given temperature expand

until the expansive force of their heat exactly balances the cohesive

force of their molecules, after which no further expansion at the

same temperature can possibly take place while the cohesive force of

the molecules remains unchanged. But if, by some means or other, the

cohesive force of the molecules become reduced, then instantly the

body will expand under the heat which it possesses, and of course a

portion of the heat will be consumed in expansion, and a cooling effect

will result. Now tension, although it does not actually lessen the

cohesive force of the molecules of the stretched body, yet produces, by

counteracting this force, the same effect; for it allows the molecules

an opportunity of performing work of expansion, and a cooling effect

is the consequence. If the piston of a steam-engine, for example, be

loaded to such an extent that the steam is unable to move it, the steam

in the interior of the cylinder will not lose any of its heat; but if

the piston be raised by some external force, the molecules of the steam

will assist this force, and consequently will suffer loss of heat in

proportion to the amount of work which they perform. The very same

occurs when tension is applied to a solid. Previous to the application

of tension, the heat existing in the molecules is unable to produce

any expansion against the force of cohesion. But when the influence of

cohesion is partly counteracted by the tension applied, the heat then

becomes enabled to perform work of expansion, and a cooling effect is

the result.

VI.

THE CAUSE OF REGELATION.[332]

There are two theories which have been advanced to explain Regelation,

the one by Professor Faraday, and the other by Professor James Thomson.

According to Professor James Thomson, pressure is the cause of

regelation. Pressure applied to ice tends to lower the melting-point,

and thus to produce liquefaction; but the water which results is

colder than the ice, and refreezes the moment it is relieved from

pressure. When two pieces of ice are pressed together, a melting takes

place at the points in contact, resulting from the lowering of the

melting-point; the water formed, re-freezing, joins the two pieces

together.

The objection which has been urged against this theory is that

regelation will take place under circumstances where it is difficult to

conceive how pressure can be regarded as the cause. Two pieces of ice,

for example, suspended by silken threads in an atmosphere above the

melting-point, if but simply allowed to touch each other, will freeze

together. Professor J. Thomson, however, attributes the freezing to

the pressure resulting from the capillary attraction of the two moist

surfaces in contact. But when we reflect that it requires the pressure

of a mile of ice—135 tons on the square foot—to lower the melting-point

one degree, it must be obvious that the lowering effect resulting

from capillary attraction in the case under consideration must be

infinitesimal indeed.

The following clear and concise account of Faraday’s theory, I quote

from Professor Tyndall’s “Forms of Water:”—

“Faraday concluded that _in the interior_ of any body, whether solid

or liquid, where every particle is grasped, so to speak, by the

surrounding particles, and grasps them in turn, the bond of cohesion

is so strong as to require a higher temperature to change the state

of aggregation than is necessary _at the surface_. At the surface of

a piece of ice, for example, the molecules are free on one side from

the control of other molecules; and they therefore yield to heat more

readily than in the interior. The bubble of air or steam in overheated

water also frees the molecules on one side; hence the ebullition

consequent upon its introduction. Practically speaking, then, the

point of liquefaction of the interior ice is higher than that of the

superficial ice....

“When the surfaces of two pieces of ice, covered with a film of the

water of liquefaction, are brought together, the covering film is

transferred from the surface to the centre of the ice, where the point

of liquefaction, as before shown, is higher than at the surface.

The special solidifying power of ice upon water is now brought

into play _on both sides of the film_. Under these circumstances,

Faraday held that the film would congeal, and freeze the two surfaces

together.”—_The Forms of Water_, p. 173.

The following appears to be a more simple explanation of the phenomena

than either of the preceding:—

The freezing-point of water, and the melting-point of ice, as Professor

Tyndall remarks, touch each other as it were at this temperature. At

a hair’s-breadth lower water freezes; at a hair’s-breadth higher ice

melts. Now if we wish, for example, to freeze water, already just about

the freezing-point, or to melt a piece of ice already just about the

melting-point, we can do this either by a change of temperature or

by a change of the melting-point. But it will be always much easier

to effect this by the former than by the latter means. Take the

case already referred to, of the two pieces of ice suspended in an

atmosphere above the melting-point. The pieces at their surfaces are

in a melting condition, and are surrounded by a thin film of water

just an infinitesimal degree above the freezing-point. The film has on

the one side solid ice at the freezing-point, and on the other a warm

atmosphere considerably above the freezing-point. The tendency of the

ice is to lower the temperature of the film, while that of the air is

to raise its temperature. When the two pieces are brought into contact

the two films unite and form one film separating the two pieces of ice.

This film is not like the former in contact with ice on the one side

and warm air on the other. It is surrounded on both sides by solid ice.

The tendency of the ice, of course, is to lower the film to the same

temperature as the ice itself, and thus to produce solidification.

It is evident that the film must either melt the ice or the ice must

freeze the film, if the two are to assume the same temperature. But the

power of the ice to produce solidification, owing to its greater mass,

is enormously greater than the power of the film to produce fluidity,

consequently regelation is the result.

VII.

LIST OF PAPERS WHICH HAVE APPEARED IN DR. A. PETERMANN’S

_GEOGRAPHISCHE MITTHEILUNGEN_ RELATING TO THE GULF-STREAM AND

THERMAL CONDITION OF THE ARCTIC REGIONS.

The most important memoir which we have on the Gulf-stream and its

influence on the climate of the arctic regions is the one by Dr. A.

Petermann, entitled “Der Golfstrom und Standpunkt der thermometrischen

Kenntniss des nord-atlantischen Oceans und Landgebiets im Jahre 1870.”

_Geographische Mittheilungen_, Band XVI. 1870.

Dr. Petermann has, in this memoir, by a different line of argument

from that which I have pursued in this volume, shown in the most clear

and convincing manner that the abnormally high temperature of the

north-western shores of Europe and the seas around Spitzbergen is owing

entirely to the Gulf-stream, and not to any general circulation such as

that advocated by Dr. Carpenter. From a series of no fewer than 100,000

observations of temperature in the North Atlantic and in the arctic

seas, he has been enabled to trace with accuracy on his charts the very

footsteps of the heat in its passage from the Gulf of Mexico up to the

shores of Spitzbergen.

The following is a list of the more important papers bearing on the

subject which have recently appeared in Dr. Petermann’s _Geogr.

Mittheilungen_:—

An English translation of Dr. Petermann’s Memoir, and of a few more in

the subjoined list, has been published in a volume, with supplements,

by the Hydrographic Department of the United States, under the

superintendence of Commodore R. H. Wyman.

The papers whose titles are in English have appeared in the American

volume. In that volume the principal English papers on the subject,

in as far as they relate to the north-eastern extension of the

Gulf-stream, have also been reprinted.

The System of Oceanic Currents in the Circumpolar Basin of the Northern

Hemisphere. By Dr. A. Mühry. Vol. XIII., Part II. 1867.

The Scientific Results of the first German North Polar Expedition. By

Dr. W. von Freeden. Vol. XV., Part VI. 1869.

The Gulf-stream, and the Knowledge of the Thermal Properties of the

North Atlantic Ocean and its Continental Borders, up to 1870. By Dr. A.

Petermann. _Geographische Mittheilungen_, Vol. XVI., Part VI. 1870.

The Temperature of the North Atlantic Ocean and the Gulf-stream. By

Rear-Admiral C. Irminger. Vol. XVI., Part VI. 1870.

Meteorological Observations during a Winter Stay on Bear Island,

1865−1866. By Sievert Tobilson. Vol. XVI., Part VII. 1870.

Die Temperatur-verhältnisse in den arktischen Regionen. Von Dr.

Petermann. Band XVI., Heft VII. 1870.

Preliminary Reports of the Second German North Polar Expedition, and of

minor Expeditions, in 1870. Vol. XVII.

Preliminary Report of the Expedition for the Exploration of the

Nova-Zembla Sea (the sea between Spitzbergen and Nova Zembla), by

Lieutenants Weyprecht and Payer, June to September, 1871. By Dr. A.

Petermann. Vol. XVII. 1871.

Der Golfstrom ostwärts vom Nordkap. Von A. Middendorff. Band XVII.,

Heft I. 1871.

Kapitän E. H. Johannesen’s Umfahrung von Nowaja Semlä im Sommer 1870,

und norwegischer Finwalfang östlich vom Nordkap. Von Th. v. Heuglin.

Band XVII., Heft I. 1871.

Die Nordpol-Expeditionen, das sagenhafte Gillis-land und der Golfstrom

im Polarmeere. Von Dr. A. Petermann. 5 Nov. 1870.

Th. v. Heuglin’s Aufnahmen in Ost-Spitzbergen. Begleitworte zur neuen

Karte dieses Gebiets. Tafel 9. 1870. Band XVII., Heft V. 1871.

Die zweite deutsche Nordpolar-Expedition, 1869−70. Schlittenreise

an der Küste Grönlands nach Norden, 8 März−27 April, 1870. Von

Ober-Lieutenant Julius Payer. Band XVII., Heft V. 1871.

Die Entdeckung des Kaiser Franz Josef-Fjordes in Ost-Grönland, August,

1870. Von Ober-Lieutenant Julius Payer. Band XVII., Heft V. 1871.

Die Erschliessung eines Theiles des nördlichen Eismeeres durch die

Fahrten und Beobachtungen der norwegischen Seefahrer Torkildsen,

Ulve, Mack Qvale, und Nedrevaag im karischen Meere, 1870. Von Dr. A.

Petermann. Band XVII., Heft III. 1871.

Die zweite deutsche Nordpolar-Expedition, 1869−70. Schlittenreise nach

Ardencaple Inlet, 8−29 Mai, 1870. Von Ober-Lieutenant Julius Payer.

Band XVII., Heft XI. 1871.

Ein Winter unter dem Polarkreise. Von Ober-Lieutenant Julius Payer.

Band XVII., Heft XI. 1871.

Die Entdeckung eines offenen Polarmeeres durch Payer und Weyprecht im

September, 1871. Von Dr. A. Petermann. Band XVII., Heft XI. 1871.

James Lamont’s Nordfahrt, Mai-August, 1871. Die Entdeckungen von

Weyprecht, Payer, Tobiesen, Mack, Carlsen, Ulve, und Smyth im Sommer,

1871.

Stand der Nordpolarfrage zu Ende des Jahres 1871. Von Dr. A. Petermann.

Band XVII., Heft XII. 1871.

Das Innere von Grönland. Von Dr. Robert Brown. Band XVII., Heft X. 1871.

Captain T. Torkildsen’s Cruise from Tromsö to Spitzbergen, July 26 to

September 26, 1871. Vol. XVIII. 1872.

The Sea north of Spitzbergen, and the most northern Meteorological

Observations. Vol. XVIII. 1872.

Results of the Observations of the Deep-sea Temperature in the Sea

between Greenland, Northern Europe, and Spitzbergen. By Professor H.

Möhn. Vol. XVIII. 1872.

The Norwegian Cruises to Nova Zembla and the Kara Sea in 1871. Vol.

XVIII. 1872.

The Cruises in the Polar Sea in 1872. Vol. XVIII. 1872.

The Cruise of Smyth and Ulve, June 19 to September 27, 1871. Vol.

XVIII. 1872.

Die fünfmonatliche Schiffbarkeit des sibirischen Eismeeres um Nowaja

Semlja, erwiesen durch die norwegischen Seefahrer in 1869 und 1870,

ganz besonders aber in 1871. Von Dr. A. Petermann. Band XVIII., Heft X.

1872.

Die neuen norwegischen Aufnahmen des nordöstlichen Theiles von Nowaja

Semlja durch Mack, Dörma, Carlsen, u. A., 1871. Von Dr. Petermann. Band

XVIII., Heft X. 1872.

Nachrichten über die sieben zurückgekehrten Expeditionen unter Graf

Wiltschek, Altmann, Johnsen, Nilsen, Smith, Gray, Whymper; die

drei Überwinterungs-Expeditionen; die Amerikanische, Schwedische,

Österreichisch-Ungarische; und die zwei neuen: die norwegische

Winter-Expedition und diejenige unter Kapitän Mack. Von Dr. A.

Petermann. Band XVIII., Heft XII. 1872.

Konig Karl-Land im Osten von Spitzbergen und seine Erreichung und

Aufnahme durch norwegische Schiffer im Sommer 1872. Von Professor H.

Möhn. Band XIX., Heft IV. 1873.

Resultate der Beobachtungen angestellt auf der Fahrt des Dampfers

“Albert” nach Spitzbergen im November und Dezember, 1872. Von Professor

Möhn. Band XIX., Heft VII. 1873.

Die amerikanische Nordpolar-Expedition unter C. F. Hall, 1871−3. Von

Dr. A. Petermann. Band XIX., Heft VIII. 1873.

Die Trift der Hall’schen Nordpolar-Expedition, 16 August bis 15

Oktober, 1872, und die Schollenfahrt der 20 bis zum 30 April, 1873. Von

Dr. A. Petermann. Band XIX., Heft X. 1873.

Das offene Polarmeer bestätigt durch das Treibholz an der Nordwestküste

von Grönland. Von Dr. A. Petermann. Band XX., Heft V. 1874.

Das arktische Festland und Polarmeer. Von Dr. Joseph Chavanne. Band

XX., Heft VII. 1874.

Die Umkehr der Hall’schen Polar-Expedition nach den Aussagen der

Offiziere. Von Dr. A. Petermann. Band XX., Heft VII. 1874.

Die zweite österreichisch-ungarische Nordpolar-Expedition unter

Weyprecht und Payer, 1872−4. Von Dr. A. Petermann. Band XX., Heft X.

1874.

Beiträge zur Klimatologie und Meteorologie des Ost-polar-Meeres. Von

Professor Möhn. Band XX., Heft V. 1874.

Kapitän David Gray’s Reise und Beobachtungen im ost-grönländischen

Meere, 1874, und seine Ansichten über den besten Weg zum Nordpol.

Original-Mittheilungen an A. Petermann, d.D., Peterhead, Dezember,

1874. Band XXI., Heft III. 1875.

VIII.

LIST OF PAPERS BY THE AUTHOR TO WHICH REFERENCE IS MADE

IN THIS VOLUME.

On the Influence of the Tidal Wave on the Earth’s Rotation and on the

Acceleration of the Moon’s Mean Motion.—_Phil. Mag._, April, 1864.

On the Nature of Heat-vibrations.—_Phil. Mag._, May, 1864.

On the Cause of the Cooling Effect produced on Solids by

Tension.—_Phil. Mag._, May, 1864.

On the Physical Cause of the Change of Climate during Geological

Epochs.—_Phil. Mag._, August, 1864.

On the Physical Cause of the Submergence of the Land during the Glacial

Epoch.—The _Reader_, September 2nd and October 14th, 1865.

On Glacial Submergence.—The _Reader_, December 2nd and 9th, 1865.

On the Eccentricity of the Earth’s Orbit.—_Phil. Mag._, January, 1866.

Glacial Submergence on the Supposition that the Interior of the Globe

is in a Fluid Condition.—The _Reader_, January 13th, 1866.

On the Physical Cause of the Submergence and Emergence of the Land

during the Glacial Epoch, with a Note by Professor Sir William

Thomson.—_Phil. Mag._, April, 1866.

On the Influence of the Tidal Wave on the Motion of the Moon.—_Phil.

Mag._, August and November, 1866.

On the Reason why the Change of Climate in Canada since the Glacial

Epoch has been less complete than in Scotland.—_Trans. Geol. Soc. of

Glasgow_, 1866.

On the Eccentricity of the Earth’s Orbit, and its Physical Relations to

the Glacial Epoch.—_Phil. Mag._, February, 1867.

On the Reason why the Difference of Reading between a Thermometer

exposed to direct Sunshine and one shaded diminishes as we ascend in

the Atmosphere.—_Phil. Mag._, March, 1867.

On the Change in the Obliquity of the Ecliptic; its Influence on the

Climate of the Polar Regions and Level of the Sea.—_Trans. Geol. Soc.

of Glasgow_, vol. ii., p. 177. _Phil. Mag._, June, 1867.

Remarks on the Change in the Obliquity of the Ecliptic, and its

Influence on Climate.—_Phil. Mag._, August, 1867.

On certain Hypothetical Elements in the Theory of Gravitation

and generally received Conceptions regarding the Constitution of

Matter.—_Phil. Mag._, December, 1867.

On Geological Time, and the probable Date of the Glacial and the Upper

Miocene Period.—_Phil. Mag._, May, August, and November, 1868.

On the Physical Cause of the Motions of Glaciers.—_Phil. Mag._, March,

1869. _Scientific Opinion_, April 14th, 1869.

On the Influence of the Gulf-stream.—_Geol. Mag._, April, 1869.

_Scientific Opinion_, April 21st and 28th, 1869.

On Mr. Murphy’s Theory of the Cause of the Glacial Climate.—_Geol.

Mag._, August, 1869. _Scientific Opinion_, September 1st, 1869.

On the Opinion that the Southern Hemisphere loses by Radiation more

Heat than the Northern, and the supposed Influence that this has on

Climate.—_Phil. Mag._, September, 1869. _Scientific Opinion_, September

29th and October 6th, 1869.

On Two River Channels buried under Drift belonging to a Period when the

Land stood several hundred feet higher than at present.—_Trans. Geol.

Soc. of Edinburgh_, vol. i., p. 330.

On Ocean-currents: Ocean-currents in Relation to the Distribution of

Heat over the Globe.—_Phil. Mag._, February, 1870.

On Ocean-currents: Ocean-currents in Relation to the Physical Theory of

Secular Changes of Climate.—_Phil. Mag._, March, 1870.

The Boulder Clay of Caithness a Product of Land-ice.—_Geol. Mag._, May

and June, 1870.

On the Cause of the Motion of Glaciers.—_Phil. Mag._, September, 1870.

On Ocean-currents: On the Physical Cause of Ocean-currents. Examination

of Lieutenant Maury’s Theory.—_Phil. Mag._, October, 1870.

On the Transport of the Wastdale Granite Boulders.—_Geol. Mag._,

January, 1871.

On a Method of determining the Mean Thickness of the Sedimentary Rocks

of the Globe.—_Geol. Mag._, March, 1871.

Mean Thickness of the Sedimentary Rocks.—_Geol. Mag._, June, 1871.

On the Age of the Earth as determined from Tidal Retardation.—_Nature_,

August 24th, 1871.

Ocean-currents: On the Physical Cause of Ocean-currents. Examination of

Dr. Carpenter’s Theory.—_Phil. Mag._, October, 1871.

Ocean-currents: Further Examination of the Gravitation Theory.—_Phil.

Mag._, February, 1874.

Ocean-currents: The Wind Theory of Oceanic Circulation.—_Phil. Mag._,

March, 1874.

Ocean-currents.—_Nature_, May 21st, 1874.

The Physical Cause of Ocean-currents.—_Phil. Mag._, June, 1874.

_American Journal of Science and Art_, September, 1874.

On the Physical Cause of the Submergence and Emergence of the Land

during the Glacial Epoch.—_Geol. Mag._, July and August, 1874.

INDEX.

Absolute heating-power of ocean-currents, 23

〃 amount of heat received from the sun per day, 26

Adhémar, M., theory founded upon a mistake in regard to

radiation, 81, 85

〃 on submergence, 368

〃 on influence of eccentricity on climate, 542

Aërial currents increased in action by formation of snow and ice, 76

〃 function of, stated, 51

〃 heat conveyed by, 27

Africa, South, glacial and inter-glacial periods of, 242

〃 boulder clay of Permian age, 300

Age and origin of the sun, 346

Air, on absorption of rays by, 59

〃 when humid, absorbs rays which agree with it in period, 59

〃 when perfectly dry incapable of absorbing radiant heat, 59

Airy, Professor, earth’s axis of rotation permanent, 7

Aitken’s, Mr., experiment on density of polar water, 129

Aland islands, striation of, 447

Alternate cold and warm periods, 236

Allermuir, striations on summit of, 441

America, low temperature in January, 72

〃 thickness of ice-sheet of North, 381

Anderson, Captain Sir James, never observed a stone on an iceberg, 282

Antarctic regions, mean summer temperature of, below

freezing-point, 63

Antarctic ice-cap, probable thickness of, 375

〃 diagram representing thickness of, 377

〃 thickness of, estimated from icebergs, 384

Antarctic snowfall, estimates of, 382

Aphelion, glacial conditions at maximum when winter solstice is at, 77

Arago, M., on influence of eccentricity on climate, 536

Arctic climate, influence of ocean-currents on, during glacial

period, 260

Arctic regions, influence of Gulf-stream on climate of, 45

〃 mean summer temperature of, 63

Arctic regions, amount of heat received by, per unit surface, 195

〃 warm periods best marked in, 258

〃 warm inter-glacial periods in, 258−265

〃 state of, during glacial period, 260

〃 evidence of warm periods in, 261

〃 occurrence of recent trees in, 261, 265

〃 evidence of warm inter-glacial periods, 293

〃 warm climate during Old Red Sandstone period in, 295

〃 glacial period during Carboniferous age in, 297

〃 warm climate during Permian period in, 301

〃 list of papers relating to, 556

Arctic Ocean, area of, 195

〃 according to gravitation theory ought to be warmer than Atlantic

in torrid zone, 195

〃 heat conveyed into, by currents, compared with that received by it

from the sun, 195

〃 blocked up with polar ice, 444

Armagh, boulder beds of, 299

Arran, Island of, glacial conglomerate of Permian age in, 299

Astronomical causes of change of climate, 10

Astronomy and geology, supposed analogy between, 355

Atlantic, atmospheric pressure on middle of, 33

〃 inability of, to heat the south-west winds without the

Gulf-stream, 34

〃 mean annual temperature of, 36

〃 mean temperature of, raised by Gulf-stream, 36, 40

〃 isothermal lines of, compared with those of the Pacific, 46

〃 area of, from equator to Tropic of Cancer, 194

〃 inquiry whether the area of, is sufficient to supply heat

according to Dr. Carpenter’s theory, 194

Atlantic, North, heat received by, from torrid zone by currents, 194

〃 according to Dr. Carpenter’s theory ought to be warmer in

temperate regions than in the torrid zone, 195

〃 great depth of warm water in, 198

〃 North, an immense whirlpool, 216

〃 above the level of equator, 221

〃 probable antiquity of, 367

〃 from Scandinavia to Greenland probably filled with ice, 451

Atmosphere-pressure in Atlantic a cause of south-west winds, 33

Atmosphere, on difference between black-bulbed and shaded thermometer

in upper strata of, 547

Australia, evidence of ice-action in conglomerate of, 295

Ayrshire, ice-action during Silurian period in, 293

Bakewell, Mr. R., on influence of eccentricity on climate, 540

Banks’s Land, discovery of ancient forest in, 261

〃 Professor Heer, on fossilized wood of, 309

Ball, Mr., objection to Canon Moseley’s results, 501

Baltic current, 171

Baltic, glaciation of islands in, 448

Baltic glacier, passage of, over Denmark, 449

Bath, grooved rock surfaces of, 464

Bay-ice grinds but does not striate rocks, 277

Belcher, Sir E., tree dug up by, in latitude 75° N., 263

〃 carboniferous fossils found in arctic regions by, 298

Belle-Isle, Strait of, observations on action of icebergs in, 276

Bell, Mr. A., on Mediterranean forms in glacial bed at Greenock, 254

Belt, Mr. Thomas, theory of the cause of glacial epochs, 415

Bennie, Mr. James, on surface geology, 468

〃 on deposits filling buried channel, 486

Blanford, Mr., on ice-action during Carboniferous age in India, 297

Borings, evidence of inter-glacial beds from, 254

〃 examination of drift by, 467

〃 journals of, 483, 484

Boulder clays of former glacial epochs, why so rare, 269

〃 a product of land-ice, 284

〃 if formed from icebergs must be stratified, 284

〃 scarcity of fossils in, 285

〃 formed chiefly from rock on which it lies, 285

〃 of Caithness a product of land-ice, 435

〃 on summit of Allermuir, 441

Boulders, how carried from a lower to a higher level, 527

Boussingault on absorption of carbon by vegetation, 428

Britain, climate of, affected most by south-eastern portion of

Gulf-stream, 33

Brown, Dr. R., cited on Greenland ice-sheet, 378, 380

〃 on inland ice of Greenland, 284

〃 on cretaceous formation of Greenland, 305

〃 on Miocene beds of the Disco district, 310

Brown, Mr. Robert, on growth of coal plants, 421

Brown and Dickeson, on sediment of Mississippi, 330

Buchan, Mr., on atmosphere-pressure in the Atlantic, 33

〃 on force of the wind, 220

Buchanan, Mr. J. Y., on vertical distribution of heat of the

ocean, 550

Buckland, Dr., observations by, on occurrence of red chalk on

Cotteswold hills, 459

Buff, Professor, on oceanic circulation, 145

Buried river channels, 466

〃 channel from Kilsyth to Grangemouth, 468

〃 section at Grangemouth, 474

〃 from Kilsyth to Clyde, 481

〃 not excavated by sea nor by ice, 469

〃 other examples of, 488−494

Caithness, difficulty of accounting for

the origin of the boulder clay of, 435

Caithness, boulder clay of, a product of land-ice, 435

〃 boulder clay not formed by icebergs, 437

〃 theories regarding the origin of the boulder clay of, 437

〃 why the ice was forced over it, 444

〃 Professor Geikie and B. N. Peach on path of ice over, 453

Cambrian conglomerate of Islay, 292

Campbell, Mr., observations of, on icebergs, 276

〃 on supposed striation of rocks by large icebergs, 278

〃 evidence that river-ice does not striate rocks, 279

Canada, change of climate less complete than in Scotland, 71

Carboniferous period of arctic regions, 298

〃 evidence of glacial epoch during, 296−298

〃 temperate climate of, 422

Carboniferous limestone, mode of formation, 433

Carpenter’s, Dr., objections examined, 141

〃 theory, mechanics of, 145

〃 idea of a 〃vertical circulation〃 stated, 153

Carpenter’s, Dr., radical error in theory of, 155

〃 on difference of density between waters of Atlantic and

Mediterranean, 168

〃 theory, inadequacy of, 191

〃 estimate of thermal work of Gulf-stream, 199

Charpentier’s, M., theory of glacier-motion, 513

Carse clays, date of, 405

Cattegat, ice-markings on shore of, 446

Cave and river deposits, 251

Chalk, erratic blocks found in, 304

〃 _débris_, conclusion of Mr. Searles Wood, 460

_Challenger’s_ temperature-soundings at equator, 119

〃 crucial test of the wind and gravitation theories, 220

Chambers, Dr. Robert, on striated pavements, 255

〃 observations on glaciation of Gothland, 446

Champlain Lake, inter-glacial bed of, 241

Chapelhall, ancient buried channel at, 491

〃 inter-glacial sand-bed, 244

Chart showing the agreement between system of currents and system

of winds, 212

Christianstadt, crossed by Baltic glacier, 450

Circulation without difference of level, 176

Climate, Secular changes of, intensified by reaction of physical

causes, 75, 76

〃 affected most by temperature of the surface of ground, 88

〃 ocean-currents in relation to, 226

〃 cold conditions of, inferred from absence of fossils, 288

〃 cold condition of, difficulty of determining, from fossil

remains, 289

〃 warm, of arctic regions during Old Red Sandstone period, 295

〃 rough sketch of the history of, during the last 60,000 years, 409

〃 of Coal period inter-glacial in character, 420

〃 alternate changes of, during Coal period, 426

Climates, Mr. J. Geikie on difficulty of detecting evidence of ancient

glacial conditions, 289

〃 evidence of, from ancient sea-bottoms, 289

Coal an inter-glacial formation, 420

Coal beds, alternate submergence and emergence during formation

of, 424

〃 preservation of, by submergence, 426

Coal period, flatness of the land during, 430

Coal plants, conditions necessary for, preservation of, 423

Coal seams, thickness of, indicative of length of inter-glacial

periods, 428

Coal seams, time occupied in formation of, 429

Coal strata, on absence of ice-action in, 429

Coal measures, oscillations of sea-level during formation of, 425

Cold periods best marked in temperate regions, 258

Colding, Dr., oceanic circulation, 95

Confusion of ideas in reference to the agency of polar cold, 179

Continental ice, inadequate conceptions of, 385

〃 absence of, during glacial epochs of Coal period, 432

Contorted drift near Musselburgh, 465

Cook, Captain, description of Sandwich Land by, 60

〃 on South Georgia, 60

Cornwall, striated rocks of, 464

Cotteswold hills, red chalk from Yorkshire found on, 459

Couthony, Mr., on action of icebergs, 275

Coutts, Mr. J., on buried channel, 493

Craig, Mr. Robert, on inter-glacial beds at Overton Hillhead and

Crofthead, 247

Craiglockhart hill, inter-glacial bed of, 245

“Crawling” theory considered, 507

“Crevasses,” origin of, according to molecular theory, 521

Cretaceous period, evidence of ice-action during, 303−305

Cretaceous age, evidence of warm periods during, 304

Cretaceous formation of Greenland, 305

Crofthead, inter-glacial bed at, 248

Cromer forest bed, 250

Crosskey, Rev. Mr., comparison of Clyde and Canada shell beds, 71

〃 on southern shells in Clyde beds, 253

Croydon, block of granite found in chalk at, 303

Crucial test of the wind and gravitation theories, 220

Crystallization, force of, a cause of glacier-motion, 523

Currents, effects of their stoppage on temperatures of equator and

poles, 42

〃 produced by saltness neutralize those produced by temperature, 106

Dalager, excursion in Greenland by, 378

Dana, Professor, on action of icebergs, 275

〃 on striations by icebergs, 275

〃 on thickness of ice-sheet of North America, 381

Darwin, Mr., on alternate cold and warm periods, 231

〃 on migration of plants and animals during glacial epoch, 395

〃 on peat of Falkland Islands, 422

Date of the 40-foot beach, 409

Date when conditions were favourable to formations of the Carse

clay, 409

Davis’ Straits, current of, 132

Dawkins, Mr. Boyd, on the animals of cave and river deposits, 251

Dawson, Principal, on esker of Carboniferous age, 296

〃 on habitats of coal plants, 424

Deflection of ocean-currents chief cause of change of climate, 68

De la Beche, Sir H. T., on influence of eccentricity on climate, 539

De Mairan, on influence of eccentricity on climate, 528

Denmark, crossed by Baltic glacier, 449−452

Denudation, method of measuring rate of, 329

〃 as a measure of geological time, 329

〃 measured by sediment of Mississippi, 330

〃 subaërial rate of, 331

〃 law which determines rate of, 333

〃 marine, trifling, 337

Deposition, rates of, generally adopted, quite arbitrary, 360

〃 rate of, determined by rate of denudation, 362

〃 range of, restricted to a narrow fringe surrounding the

continents, 364

〃 area of, 365

〃 during glacial epoch probably less than present, 366

Deposits from icebergs cannot be wholly unstratified, 437

Despretz, tables by, of temperature of maximum density of

sea-water, 117

Desor, M., on tropical fauna of the Eocene formation in

Switzerland, 306

Derbyshire, breaks in limestone of, marks of cold periods, 434

Derbyshire limestone a product of inter-glacial periods, 434

Devonshire, boulder clay discovered in, 463

Diagram illustrating descent of water from equator to poles, 155

〃 showing variations of eccentricity, 313

〃 illustrative of fluidity of interior of the earth, 396

〃 showing formation of coal beds, 426

Dick, Mr., chalk flints in boulder clay, 454

Dick, Mr. R., on buried channel, 491

Difference of level essential to gravitation theory, 176

Dilatation of sea-water by increase of temperature calculated by Sir

John Herschel, 116

Disco district, Dr. R. Brown cited on Miocene beds of, 310

Disco Island, Upper Miocene period of, 307−308

Distribution, how effected by ocean-currents, 231

Dove, Professor, method of constructing normal temperature tables

by, 40

〃 on mean annual temperature, 401

Dover, mass of coal imbedded in chalk found at, 303

Drayson, Lieutenant-Colonel, on obliquity of ecliptic, 410

Drayson, Lieutenant-Colonel, theory of the cause of the glacial

epoch, 410

Drift, examination by borings, 467

Drumry, deep surface deposits at, 482

Dubuat’s, M., experiments, 182

〃 experiments by, on water flowing down an incline, 120

Duncan, Captain, on under current in Davis’ Strait, 134

Dürnten lignite beds, 240

Dürnten beds an example of inter-glacial coal formation, 433

Durham, buried river channel at, 488

Earth’s axis of rotation permanent, 7

Earth, mean temperature of, increased by water at equator, 30

〃 not habitable without ocean-currents, 54

〃 mean temperature of, greatest in aphelion, 77, 78

〃 centre of gravity of, effects of ice-cap on, 370, 371

Eccentricity of the earth’s orbit, Mr. Stockwell’s researches

regarding, 54

〃 primary cause of change of climate, 54

〃 primary cause of glacial epochs, 77

〃 how it affects the winds, 228

〃 tables of, 314−321

〃 its influence on temperature, 323

〃 explanation of tables of, 324

〃 De Marian, on influence of, on climate, 528

〃 Sir J. F. Herschel, on influence of, on climate, 529

〃 Œpinus, on influence of, on climate, 529

〃 R. Kirwan, on influence of, on climate, 529

〃 of planetary orbits, superior limits as determined by Lagrange,

Leverrier, and Mr. Stockwell, 531

〃 Sir Charles Lyell, on influence of, on climate, 529, 535

〃 M. Arago, on influence of, on climate, 536

〃 Baron Humboldt, on influence of, on climate, 538

〃 Sir H. T. de la Beche, on influence of, on climate, 539

〃 Professor Phillips, on influence of, on climate, 539

〃 Mrs. Somerville, on influence of, on climate, 540

〃 L. W. Meech, on influence of, on climate, 540

〃 Mr. R. Bakewell, on influence of, on climate, 540

〃 M. Jean Reynaud, on influence of, on climate, 541

〃 M. Adhémar, on influence of, on climate, 542

Equator, reduction of level by denudation, 336

Ecliptic, supposed effect of a change of obliquity of, 8

〃 changes of, effects on climate, 398−417

〃 obliquity of, Lieutenant-Colonel Drayson on, 410

Emergence, physical cause of, 368

England, inter-glacial beds of, 249

〃 glacial origin of Old Red Sandstone of, 294

〃 ice-action during Permian period in, 298

〃 North of, ice-sheet of, 456

〃 ice-sheet of South of, 463

Eocene period, total absence of fossils in flysch, 286

〃 glacial epoch of, 305

Eocene and Miocene periods, date of, 357

Equator, heat received per square mile at, 26

〃 temperature of earth increased by water at, 30

〃 and poles, effects of stoppage of currents on temperature of, 42

〃 surface-currents warmer than the under currents, 92

〃 heat transferred by currents from southern hemisphere compared

with that received by land at, 93

〃 temperature soundings at, 119

〃 temperature of sea at, decreases most rapidly at the surface, 119

〃 heat received by the three zones compared with that received by

the, 194

〃 migration across, 234

〃 glaciation of, 234

Equatorial current, displacement of, 229

Erratic blocks in stratified rocks, evidence of former land-ice, 269

〃 in chalk, 304

〃 why not found in coal strata, 432

Erratics extend further south in America than in Europe, 72

Etheridge, R., jun., on glacial conglomerate in Australia of Old Red

Sandstone age, 295

Europe, influence of Gulf-stream on climate of, 31

〃 effect of deflection of Gulf-stream on condition of, 68

〃 glacial condition of, if Gulf-stream was stopped, 71

〃 river systems of, unaltered since glacial period, 393

Faraday, Professor, on cause of regelation, 554

Faroe Islands glaciated by land-ice from Scandinavia, 450

Ferrel, Mr., on Dr. Carpenter’s theory, 126

〃 argument from the tides, 184

Findlay, Mr. A. G., objection by, considered, 31, 203

〃 estimate of heat conveyed by Gulf-stream, 206

Fisher, Rev. O., on the 〃trail〃 of Norwich, 251

〃 on glacial submergence, 387

Fitzroy, Admiral, on temperature of Atlantic, 36

Fluid molecules crystallize in interstices, 523

Fluvio-marine beds of Norwich, 250

“Flysch” of Eocene period, absence of fossils in, 286

〃 of Switzerland of glacial origin, 306

Fogs prevent the sun’s heat from melting ice and snow in arctic

regions, 60

Forbes, Professor J. D., method adopted by, of ascertaining

temperatures, 48

〃 on temperature of equator and poles, 48

〃 on the conductivity of different kinds of rock, 86

〃 on underground temperature, 86

〃 experiments by, on the power of different rocks to store up

heat, 86

Forest bed of Cromer, 250

Former glacial periods, 266−310

〃 why so little known of, 266

〃 geological evidence of, 292

France, evidence of ice-action during Carboniferous period in, 296

Fraserburgh, glaciation of, 450

〃 crossed by North Sea ice, 454

Fundamental problem of geology, 1

Ganges, amount of sediment conveyed by, 331

Gases, radiation of, 38

Gastaldi, M., on the Miocene glacial epoch of Italy, 306

Geikie, Professor, on geological agencies, 1

〃 on inter-glacial beds of Scotland, 243

〃 remarks on inter-glacial beds, 245

〃 on striated pavements, 256

〃 on ice-markings on Scandinavian coast, 281

〃 striated stones found in carboniferous conglomerate by, 296

〃 on sediment of European rivers, 332

〃 on modern denudation, 332

〃 suggestion regarding the loess, 452

〃 on striation of Caithness, 453

〃 on buried channel at Chapelhall, 491

〃 and Mr. James, on glacial conglomerate of Lower Carboniferous

age, 296

Geikie, Mr. James, on Crofthead inter-glacial bed, 248

〃 on the gravels of Switzerland, 268

〃 on difficulty of recognising former glacial periods, 289

〃 on Cambrian conglomerate of north-west of Scotland, 293

〃 on ice-action in Ayrshire during Silurian period, 293

〃 on boulder conglomerate of Sutherland, 301

〃 on buried channels, 492

Geogr. Mittheilungen, list of papers in, relating to arctic

regions, 556

Geological agencies climatic, 2

Geological principle, nature of, 4

Geological climates, theories of, 6

Geological time, 311−359

〃 measurable from astronomical data, 311

〃 why it has been over-estimated, 325

〃 method of measuring, 328, 329

〃 Professor Ramsay on, 343

Geology, fundamental problem of, 1

〃 a dynamical science, 5

〃 and astronomy, supposed analogy between, 355

German Polar Expedition on density of polar water, 151

〃 list of papers relating to, 556

German Ocean once dry land, 479

Germany, Professor Ramsay on Permian breccia of, 300

Gibraltar current, Dr. Carpenter’s theory of, 167

〃 cause of, 215

Glacial conditions increased by reaction of various physical

causes, 75

〃 reach maximum when winter solstice arrives at aphelion, 77

Glacial epoch, date of, 327

〃 circumstances which show recent date of, 341

〃 Mr. Belt’s theory of cause of, 415

Glacial epochs dependent upon deflection of ocean-currents, 68

〃 caused primarily by eccentricity, 77

〃 why so little known of, formerly, 266

〃 boulder clays of former, why so rare, 269

〃 geological evidence of former, 292

Glacial period in America more severe than in Western Europe, 73

〃 mean temperature of the earth greatest at aphelion during, 78

〃 records of, fast disappearing, 270

〃 of the Eocene formation, 305

Glacial periods, indirect evidence of, in Eocene and Miocene

formations, 287

〃 difficulty of determining, from fossil remains, 289

Glacial submergence resulting from displacement of the earth’s centre

of gravity, 389

Glaciation a cause of submergence, 390

〃 remains of, found chiefly on land surfaces, 267

〃 of Scandinavia inexplicable by theory of local glaciers, 448

Glacier des Bois, 497

Glacier-motion, Canon Moseley’s theory of, 507

〃 Professor James Thomson’s theory of, 512

〃 M. Charpentier’s theory of, 513

〃 molecular, 516

Glacier-motion, present state of the question, 514

〃 molecular theory of, 514−527

〃 heat necessary to, 515

〃 due to force of crystallization, 523

〃 due chiefly to internal molecular pressure, 523

Glaciers, pressure exerted by, 274

〃 physical cause of the motion of, 495−527

〃 difficulties in accounting for motion of, 495

Glasgow, actual January temperature of, 28° above normal, 72

Godwin-Austen, Mr., on ice-action during the Carboniferous period in

France, 296

〃 on evidence of ice-action during Cretaceous period, 303

〃 on mass of coal found in chalk at Dover, 304

〃 on the flatness of the land during Coal period, 430

Gothland, glaciation of, 446

Grangemouth, buried river channel at, 468

〃 surface-drift of, 484

Gravitation, the whole work of, performed by descent of water down the

slope, 154

〃 of sun’s mass, 348

〃 insufficient to account for sun’s heat, 349, 350

Gravitation theory, its relation to the theory of Secular changes of

climate, 97

〃 three modes of determining it, 115

〃 mechanics of, 145

〃 of the Gibraltar current, 167

〃 inadequacy of, 191

〃 _crucial_ test of, 220

〃 of the sun’s heat, 346−355

Gravity, force of, impelling water from equator to poles, 119, 120

〃 force of, insensible at a short distance below the surface, 120

〃 work performed by, 150

〃 diagram illustrating the action of, in producing currents, 155

〃 amount of work performed by, due solely to _difference_ of

temperature between equatorial and polar waters, 164

〃 specific difference in, between water of Atlantic and

Mediterranean insufficient to produce currents, 169

〃 centre of, displacement, by polar ice-cap, 368

Greenland, summer warm if free from ice, 59

〃 receives as much heat in summer as England, 66

〃 continental ice free from clay or mud, 284

〃 North, warm climate during Oolitic period in, 302

〃 Cretaceous formation of, 305

Greenland, evidence of warm conditions during Miocene period in, 307

〃 Professor Heer cited on Miocene flora of, 308, 309

〃 state of, during glacial period, 259

〃 effect of removal of ice from, 260

Greenland ice-sheet, probable thickness of, 378

〃 invaded the American continent, 445

Greenland inland ice, 379

Gulf-stream, estimate of its volume, 24

〃 United States’ coast survey of, 24

〃 absolute amount of heat conveyed by, 25, 26

〃 heat conveyed by, compared with that carried by aërial

currents, 27

〃 heat conveyed by, compared with that received by the frigid zone

from the sun, 27

〃 influence on climate of Europe, 31

〃 efficiency of, due to the slowness of its motion, 32

〃 climate of Britain influenced by south-eastern portion of, 33

〃 heat conveyed by, compared with that derived by temperate regions

from the sun, 34

〃 heat of, expressed in foot-pounds of energy, 35

〃 mean temperature of Atlantic increased one-fourth by, 36

〃 the only current that can heat arctic regions, 45

〃 influence of, on climate of arctic regions, 45

〃 the compensating warm current, 46

〃 palæontological objections to influence of, 53

〃 agencies which deflect the, in glacial periods, 69

〃 result, if stopped, 71

〃 large portion of the heat derived from southern hemisphere, 94

〃 Lieut. Maury on propulsion of, by specific gravity, 102

〃 contradictory nature of, the causes supposed by Lieut. Maury for

the, 110

〃 higher temperature of, considered by Lieut. Maury as the real

cause of its motion, 111

〃 amount of heat conveyed by, not over-estimated, 197

〃 amount of heat conveyed by, 192

〃 amount of heat conveyed by, compared with that by general oceanic

circulation, 194

〃 heat conveyed by, compared with that received by torrid zone from

the sun, 194

〃 heat conveyed by, into Arctic Ocean compared with that received by

it from the sun, 195

〃 Capt. Nares’s observations of, 198

〃 Dr. Carpenter’s estimate of the thermal work of, 199

Gulf-stream, volume and temperature of, according to Mr. A. G.

Findlay, 203, 206

〃 erroneous notion regarding depth of, 207

〃 list of papers relating to, 556

Haughton, Professor, on recent trees in arctic regions, 263

〃 on fragments of granite in carboniferous limestone, 296

〃 on coal beds of arctic regions, 298

〃 on _Ammonites_ of Oolitic period in arctic regions, 303

Hayes, Dr., on Greenland ice-sheet, 379

Heat received from the sun per day, 26

〃 received by temperate regions from the sun, 34

〃 radiant, absorbed by ice remains insensible, 60

〃 sun’s, amount of, stored up in ground, 87

〃 transferred from southern to northern hemisphere, 93

〃 internal, supposed influence of, 176

〃 received by the three zones compared with that received by the

equator, 194

〃 amount radiated from the sun, 346

〃 received by polar regions 11,700 years ago, 403

〃 necessary to glacier-motion, 515

〃 how transmitted through ice, 517

Heat-vibrations, nature of, 544

Heath, Mr. D. D., on glacial submergence, 387

Heer, Professor, on Dürnten lignite beds, 241

〃 on Miocene flora of Greenland, 308−310

〃 on Miocene flora of Spitzbergen, 309

Hills, ice-markings on summits of, as evidence of continental ice, 458

Helmholtz’s gravitation theory of sun’s heat, 348

Henderson, Mr. John, on inter-glacial bed at Redhall quarry, 247

Herschel, Sir John, on influence of eccentricity, 11

〃 estimate of the Gulf-stream by, 25

〃 on the amount of the sun’s heat, 26

〃 on inadequacy of specific gravity to produce ocean-currents, 116

〃 his objections to specific gravity not accepted, 117

〃 on influence of eccentricity on climate, 529

Home, Mr. Milne, on buried river channels, 478

Hooker, Sir W., on tree dug up by Capt. Belcher, 264

Hooker, Dr., on preponderance of ferns among coal plants, 421

Horne, Mr. J., on conglomerates of Isle of Man, 295

Hoxne, inter-glacial bed of, 241

Hudson’s Bay, low mean temperature of, in June, 62

Hull, Professor, on ice-action during Permian age in Ireland, 299

〃 on equable temperature of Coal period, 421

〃 on estuarine origin of coal measures, 424

Hull, buried channel at, 489

Humboldt, Baron, on loss of heat from radiation, 82

〃 on rate of growth of coal, 429

〃 on influence of eccentricity on climate, 538

Humphreys and Abbot on sediment of Mississippi, 330

Ice, latent heat of, 60

Ice, effects of removal of, from polar regions, 64

〃 heat absorbed by, employed wholly in mechanical work, 60

〃 slope necessary for motion of continental, 375

〃 does not shear in the solid state, 516

〃 how heat is transmitted through, 517

〃 how it can ascend a slope, 525

〃 how it can excavate a rock basin, 525

Icebergs do not striate sea-bottom, 272

〃 markings made by, are soon effaced, 273

〃 exerting little pressure perform little work, 273

〃 behaviour of, when stranded, 274

〃 action of, on sea-bottoms, 274

〃 rocks ground smooth, but not striated by, 276

〃 stones seldom seen on, 281

〃 evidence of, in Miocene formation of Italy, 307

〃 comparative thickness of arctic and antarctic, 381

〃 great thickness of antarctic, 382

Ice-cap, effects of, on the earth’s centre of gravity, 369

〃 probable thickness of antarctic, 375

〃 evidence from icebergs as to thickness of antarctic, 383−385

Ice-markings, modern, observed by Sir Charles Lyell, 280

Ice-sheet, probable thickness of in Greenland, 380

〃 of north of England, 456

Ice-worn pebbles found on summit of Allermuir, 441

Iceland, lignite of Miocene age in, 308

〃 probably glaciated by land-ice from North Greenland, 451

India, evidences of glacial action of Carboniferous age in, 297

Indian Ocean, low temperature at bottom, 123

Internal heat, no influence on climate, 6

〃 supposed influence of, 176

Inter-tropical regions, greater portion of moisture falls as rain, 29

Inter-glacial bed at Slitrig, 243

〃 at Chapelhall, 244

〃 of Craiglockhart hill, 245

〃 at Kilmaurs, 248

Inter-glacial beds, Professor Geikie on, 243

〃 of Dürnten, 240

〃 of Scotland, 243

〃 of England, 249

〃 at Norwich, 250

〃 evidence of, from borings, 254

Inter-glacial character of cave and river deposits, 251

Inter-glacial climate during Old Red Sandstone period in arctic

regions, 295

Inter-glacial periods, 236

〃 reason why overlooked, 237

〃 of Switzerland, 239

〃 evidence of, from shell-beds, 252

〃 evidence from striated pavements of, 255

〃 reasons why so few vestiges remain of, 257

〃 in arctic regions, 258−265

〃 of Silurian age in arctic regions, 293

〃 of Carboniferous age in arctic regions, 297

〃 of Eocene formation in Switzerland, 306

〃 formation of coal during, 420

〃 length of, indicated by thickness of coal-seams, 428

Inglefield, Captain, erect trees found in Greenland by, 309

Ireland, on ice-action during Permian age in, 299

Isbister, Mr., on carboniferous limestone of arctic regions, 297

Islay, Cambrian conglomerate of, 292

Italy, glacial epoch of Miocene period in, 306

Jack, Mr. R. L., on deflection of ice across England, 461

Jamieson, Mr. T. F., on boulder clay of Caithness, 435

〃 opinion that Caithness was glaciated by floating ice, 437

〃 on thickness of ice in the north Highlands, 439

〃 glaciation of headland of Fraserburgh, 450, 455

January temperature of Glasgow and Cumberland, difference between, 72

Jeffreys, Mr. Gwyn, on Swedish glacial shell beds, 253

Johnston, Dr. A. Keith, on coast-line of the globe, 337

Joule’s, Dr., experiments on the thermal effect of tension, 552

Judd, Mr., on boulders of Jurassic age in the Highlands, 302

Jukes, Mr., on warm climate of North Greenland during Oolitic period, 302

July, why hotter than June, 89

Kane, Dr., on mean temperature of Von Rensselaer Harbour, 62

Karoo beds, glacial character of, 301

〃 evidence of subtropical during deposition of, 301

Kelvin, ancient bed of, 481

Kielsen, Mr., excursion upon Greenland ice-sheet, by, 378

Kilmours, inter-glacial bed at, 248

Kirwan, Richard, on influence of eccentricity on climate, 529

Kyles of Bute, southern shell bed in, 253

Labrador, mean temperature of, for January, 72

〃 Mr. Packard on glacial phenomena of, 282

Lagrange, M., on eccentricity of the earth’s orbit, 54

〃 table of superior limits of eccentricity, 531

Land at equator would retain the heat at equator, 30

〃 radiates heat faster than water, 91

〃 elevation of, will not explain glacial epoch, 391

〃 submergence and emergence during glacial epoch, 368−397

〃 successive upheavals and depressions of, 391

Land-ice necessarily exerts enormous pressure, 274

〃 evidence of former, from erratic blocks on stratified

deposits, 269

Land-surfaces, remains of glaciation found chiefly on, 267

〃 (ancient) scarcity of, 268

Laplace, M., on obliquity of ecliptic, 398

Laughton, Mr., on cause of Gibraltar current, 215

Leith Walk, inter-glacial bed at, 246

Leverrier, M., on superior limit of eccentricity, 54

〃 on obliquity of ecliptic, 398

〃 table, by, of superior limits of eccentricity, 531

〃 formulæ, of, 312

Lignite beds of Dürnten, 240

Loess, origin of, 452

London, temperature of, raised 40° degrees by Gulf-stream, 43

Lomonds, ice-worn pebbles found on, 439

Lubbock, Sir J., on cave and river deposits, 252

Lucy, Mr. W. C., on glaciation of West Somerset, 463

〃 on northern derivation of drift on Cotteswold hills, 460

Lyell’s, Sir C., theory of the effect of distribution of land and

water, 8

〃 on action of river-ice, 280

〃 on tropical character of the fauna of the Cretaceous

formation, 305

〃 on warm conditions during Miocene period in Greenland, 307

〃 on influence of eccentricity, 324

〃 on sediment of Mississippi, 331

〃 on comparison of existing rocks with those removed, 362

〃 on submerged areas during Tertiary period, 392

〃 on change of obliquity of ecliptic, 418

〃 on climate best adapted for coal plants, 420

〃 on influence of eccentricity on climate, 529, 535

Mackintosh, Mr., observations on the glaciation of Wastdale Crag, 457

Magellan, Straits of, temperature at midsummer, 61

Mahony, Mr. J. A., on Crofthead inter-glacial bed, 248

Mälar Lake crossed by ice, 447

Man, Isle of, Mr. Cumming on glacial origin of Old Red Sandstone

of, 294

Mars, uncertainty as to its climatic condition, 80

〃 objection from present condition of, 79

Marine denudation trifling, 337

Markham, Clements, on density of Gulf-stream water, 129

〃 on motion of icebergs in Davis’ Straits, 133

Martins’s, Professor Charles, objections, 79

Mathews, Mr., on Canon Moseley’s experiment, 499

Maury, Lieutenant, his estimate of the Gulf-stream, 25

〃 his theory examined, 95

〃 on temperature as a cause of difference of specific gravity, 102

〃 on difference of saltness as a cause of ocean-currents, 103

〃 discussion of his views of the causes of ocean-currents, 104

〃 his objection to wind theory of ocean-currents, 211

McClure, Captain, discovery of ancient forest in Banks’s Land, 261

Mecham, Lieutenant, discovery of recent trees in Prince Patrick’s

Island, 261

Mechanics of gravitation theory, 145

Mediterranean shells in glacial shell bed of Udevalla, 253

〃 shells in glacial beds at Greenock, 254

Meech, Mr., on amount of sun’s rays cut off by the atmosphere, 26

〃 on influence of eccentricity on climate, 540

Melville Island, summer temperature of, 65

〃 discovery of recent trees in, 262

〃 plants found in coal of, 298

Mer de Glace, Professor Tyndall’s observations on, 498

Meteoric theory of sun’s heat, 347

Method of measuring rate of denudation, 329

Miller, Hugh, on absence of hills in the land of the Coal period, 431

Migration of plants and animals, how influenced by ocean-currents, 231

〃 across equator, 234

Millichen, remarkable section of drift at, 483

Miocene glacial period, 286

Miocene period, glacial epoch of, in Italy, 306

Miocene, warm period of, in Greenland, 307

Miocene and Eocene periods, date of, 357

Mississippi, amount of sediment in, 330

〃 volume of, 330

Mitchell, Mr., on cause of Gulf-stream, 131

Molecular theory of origin of 〃Crevasses,” 521

〃 modification of, 523

Moore, Mr. J. Carrick, on ice-action of Silurian age in

Wigtownshire, 293

Moore, Mr. Charles, on grooved rocks in Bath district, 464

Morlot, M., on inter-glacial periods of Switzerland, 240

Moseley, Canon, experiment to determine unit of shear, 498

〃 on motion of glaciers, 498

〃 unit of shear uncertain, 504

〃 his theory examined, 507

Motion of the sea, how communicated to a great depth, 136

Motion in space, origin of sun’s heat, 353

Mühry, M., on circumpolar basin, 133, 556

Mundsley, freshwater beds of, 250

Muncke on the expansion of sea-water, 118

Murchison, Sir R., on southern shells at Worcester, 253

〃 on trees in arctic regions, 262

〃 on striation of islands in the Baltic, 448

Murphy’s, Mr., theory, 66

Musselburgh, section of contorted drift near, 465

Nares, Captain, on low temperature of antarctic regions, 64

〃 discovery of great depth of warm water in North Atlantic, 198

〃 estimate of volume and temperature of Gulf-stream, 198

〃 temperature soundings by, 119, 222

〃 thermal condition of Southern Ocean, 225

Natal, boulder clay of, 300

Newberry, Professor, on inter-glacial peat-bed of Ohio, 249

〃 on boulder of quartzite found in seam of coal, 296

Nicholson, Dr., on Wastdale Crag, 457

Nicol, Professor, on inter-glacial buried channel, 244

Nordenskjöld, Professor, on inland ice of Greenland, 379

North Sea rendered shallow by drift deposits, 443

Northern seas probably filled with land-ice during glacial period, 438

Northern hemisphere, condition of, when deprived of heat from

ocean-current, 68

Norway, southern species in glacial shell beds, 253

Norwich Crag, its glacial character, 249

Norwich fluvio-marine beds, 250

Norwich inter-glacial beds, 250

Obliquity of ecliptic, its effects on climate, 398−419

〃 change of, influence on sea-level, 403

〃 Lieutenant-Colonel Drayson on, 410

〃 Mr. Belt on change of, 415

〃 Sir Charles Lyell on change of, 418

Ocean, imperfect conception of its area, 135

〃 condition of, inconsistent with the gravitation theory, 136

〃 low temperature at bottom a result of under currents, 142

〃 circulation, pressure as a cause of, 187

〃 antiquity of, 367

Ocean-currents, absolute heating power of, 23

〃 influence of, on normal temperatures overlooked, 40

〃 maximum effects of, reached at equator and poles, 49

〃 compensatory at only one point, 49

〃 heating effects of, greatest at the poles, 50

〃 cooling effects of, greatest at equator, 50

〃 earth not habitable without, 51

〃 result of deflection into Southern Ocean, 68

〃 palæontological objections against influence of, 53

〃 deflection of, the chief cause of changes of climate, 68

〃 how deflected by eccentricity, 69

〃 deflected by trade-winds, 70

〃 temperature of southern hemisphere lowered by transference of

heat to northern hemisphere by, 92

〃 take their rise in the Southern Ocean, 92

〃 cause of, never specially examined by physicists, 95

〃 if due to specific gravity, strongest on cold hemisphere, 97

〃 if due to eccentricity, strongest on warm hemisphere, 97

〃 if due to specific gravity, act only by descent, 99

〃 mode by which specific gravity causes, 100, 101

〃 the true method of estimating the amount of heat conveyed by, 207

〃 due to system of winds, 212

〃 system of, agrees with the system of the winds, 213

〃 how they mutually intersect, 219

〃 in relation to climate, 226

〃 direction of, depends on direction of winds, 227

〃 causes which deflect, affect climate, 228

〃 in relation to distribution of plants and animals, 231

〃 effects of, on Greenland during glacial period, 260

Œpinus on influence of eccentricity on climate, 529

Ohio inter-glacial beds, 249

Old Red Sandstone, evidence of ice-action in conglomerate of, 294, 295

Oolite of Sutherlandshire, 454

Oolitic period, evidence of ice-action during, 301−303

〃 warm climate in North Greenland during, 302

Organic remains, absence of, in glacial conglomerate of Upper Miocene

period, 286