lord high admiral during the visit of his royal highness to the seaports, was promoted to the rank of captain, July 7th, 1827. In 1834 he was appointed to the "North Star," and was for a time employed on a survey of the coast of Central America. He became rearadmiral in July, 1854. Upon his marriage, in 1838, he took up his residence at Swinton Park, and soon after became magistrate for the north and west districts of Yorkshire; and in 1848 was high-sheriff. He was a man of great benevolence of character, and a benefactor of the Church, having built and endowed one near Masham, and another in Devonshire. He built a number of alms-houses for the benefit of the poor, beside contributing largely to the different schools in and near Masham.

HATHERTON, Rt. Hon. EDWARD JOHN LITTLETON, Lord, born March 18th, 1791, died at Teddesley Park, May 4th, 1863. He was the only son of Moreton Walhouse, Esq., of Hatherton, but on the death of his great uncle, Sir Edward Littleton, Bart., he inherited the estates and assumed the name of Littleton. He was educated at Rugby, graduating at Brasennose College, Oxford, and had barely attained his majority when, in 1812, he succeeded to the representation of Staffordshire.

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The business habits of Mr. Littleton, his tact and good judgment, soon gained him a high station in the Commons, and he was long considered one of the best authorities on the forms and procedure of Parliament. He succeeded his uncle in the chairmanship of the Staffordshire and Worcestershire Canal Company, an office he retained to his death. Mr. Littleton was a constant supporter of Catholic Emancipation, the advocacy of which measure for many years imperilled his seat. He was also one of the principal framers of the wings" of the Catholic Relief Bill, as well as one of the promoters of the unsuccessful measure for the payment of the Catholic clergy. He was a supporter of Mr. Canning's short lived ministry, and on the accession of Lord Grey to the premiership, he immediately joined the whig party. Upon the passage of the measures of Reform, the Cabinet intrusted to him the difficult duty of planning the boundaries of the newly enfranchised towns and divisions of counties, and of extending the limits of the old parliamentary cities and boroughs, and with very few and immaterial modifications the suggested boundaries became the law of the land. On the dissolution of Parliament in 1835 he was again returned for South Stafford, and the same year was created a peer, by the title of Baron Hatherton, of Hatherton. In 1854 he was appointed Lordlieutenant of Staffordshire. During the Crimean War he devoted himself to the organization of the militia of his county, and latterly to the formation of Volunteer Rifle Corps. His hospitality was profuse, and he annually entertained public men of all parties and men of letters, together with many distinguished

foreigners visiting England; and no man of his rank took a deeper interest in the welfare of the working classes.

HEAT. An important revolution has been going on within the last few years in the philosophy of physics, which must have the effect of changing our fundamental conceptions of the nature and relations of force. The publication in London of Prof. Tyndall's new and admirable work on "Heat as a Mode of Motion," must be regarded as an important result of the progress of thought in this direction, and the republication of this book in New York as it is the first regular work upon this subject in America-by bringing forward the new views, and opening the general discussion, has a special interest at the present time.

Every reflecting student of physical science has no doubt been perplexed by the phrase "imponderable forms of matter," which is applied in our text books to beat, light, electricity, and magnetism. No one has proposed to rank chemical affinity in this category, or to consider the force which produces or resists motion as an imponderable. By this hypothesis agencies, which are closely allied, and unquestionably of a kindred nature, have been so completely separated as to involve the whole subject in absurdity, and prevent the progress of rational and consistent theory.

According to the old view, caloric is regarded as the substance of heat-as a subtile, imponderable matter which flows in and out of bodies, warming and cooling them according to its quantity. When heat disappears, the caloric is said to become "latent; as different bodies require different quantities of heat to raise them through the same degree of temperature, they are said to have different "capacities" for containing or holding the caloric fluid; while if a body becomes heated by rubbing, it is because its latent heat is liberated by friction. So also with electricity. By friction of various bodies the equilibrium of the all-pervading "electric fluid" is supposed to be disturbed. When the glass plate of the electrical machine is rubbed by the cushion the effect is to draw up the "electric fluid" out of the earth, the common reservoir," and when a circuit of wire becomes electrically active, it is because a current of the "electric fluid" is flowing round and round through the conductors. This old hypothesis has no doubt been of important service in its day. Before the time had come to perceive the true relations of these agencies, the best that could be done was to borrow the conception and language of fluids, and apply them to these subtile and mobile effects of force that had to be represented in some way. But the hypothesis was grossly material; caloric was regarded as matter, as truly and essentially as gold or iron. And as the fundamental mod ern conception of the chemical elements is that they cannot be transmuted one into the others, so the radical conception of the imponderables was that as each had an independent material

existence, they could not be transformed into each other. This hypothesis being the very reverse of the fact, its dogmas have long offered a barrier to the true course of physical investigation.

It is now established that the forces possess none of the attributes of matter-they are not entities-substantive things, endowed with peculiar, persistent individual properties, but they are modes of motion, or forms of movement in common matter, and are convertible one into another. It has long been known, for example, that heat, as in the case of the steam engine, produces mechanical force, while mechanical force, as in the case of friction, produces heat. But in what way is the effect related to the cause? The old hypothesis assumes the intervention of a fluid, which, so long as its agency is entertained, blinds us to the simplicity of the facts. The new explanation says that the conception of the fluid is superfluous-that heat actually passes into mechanical motion, and mechanical motion actually passes into heat, or that there is a conversion of one into another. So with all the other forces known as "imponderables;" they are mutually convertible into one another-a fact which has been described by Mr. Grove, under the phrase "correlation of forces." In his able treatise upon this subject, which, we are glad to learn, is to be republished in this country, he gives a lucid account of the principle from which the following paragraphs are abridged.

The various affections of matter, which constitute the main objects of experimental physics -namely, heat, light, electricity, magnetism, chemical affinity, and motion, are all correlative, or have a reciprocal dependence. Neither, taken abstractly, can be said to be the essential cause of the others, but either may produce or be convertible into any of the others. Thus heat may mediately or immediately produce electricity, electricity may produce heat, and so of the rest, each merging itself as the force it produces becomes developed. The same must hold good of other forces, it being an irresistible inference from observed phenomena, that a force cannot originate otherwise than by the dissolution of some preexisting force or forces. The term correlation, strictly interpreted, means a necessary mental or reciprocal dependence of two ideas inseparable even in mental conception; thus the idea of height cannot exist without involving the idea of depth; the idea of parent cannot exist without involving the idea of offspring. The probability is that, if not all, the greater number of physical phenomena are correlative, and that without a duality of conception the mind cannot form an idea of them. Thus matter and force are correlates in the strictest sense of the word; the conception of the existence of the one, involves the conception of the existence of the other. The correlation of forces implies their reciprocal production; that any force capable of producing another may, in its turn, be produced by

it-nay more, can be itself resisted by the force it produces in proportion to the energy of such production, as action is ever accompanied and resisted by reaction. Thus the action of an electro-magnetic machine is reacted upon by the magneto-electricity developed by the action. With regard to the forces of electricity and magnetism in a dynamic state, we cannot electrize a substance without magnetizing it—we cannot magnetize without electrizing it. Each molecule, the instant it is affected by one of these forces, is affected by the other, but in transverse directions; the forces are inseparable and mutually dependent; correlative, but not identical.

In many cases where one physical force is excited, all the others are also set in action. Thus, when a substance, such as sulphuret of antimony, is electrified, at the instant of electrization, it becomes magnetic in directions at right angles to the lines of electrical force; at the same time it becomes heated to an extent greater or less according to the intensity of the electric force. If this intensity is exalted to a certain point, the sulphuret becomes luminous, or light is produced; it expands, consequently motion is produced; and it is decomposed, therefore chemical action is produced.

Motion, the most obvious, the most distinctly conceived of all the affections of matter will directly produce heat and electricity, and electricity, being produced by it, will produce magnetism. Light also is readily produced by motion; either directly, as when accompanying the heat of friction, or immediately by electricity resulting from motion. In the decompositions and compositions which the terminal wires proceeding from the conductors of an electrical machine develop when immersed in different chemical media, we get the production of chemical affinity by electricity, of which motion is the initial source.

If heat be now taken as the starting point, we shall find that the other modes of force may be readily produced by it. Motion is so generally, if it be not invariably, the immediate effect of heat, that we may almost, if not entirely, resolve heat into motion, and view it as a mechanically repulsive force tending to move the particles of all bodies, or to separate them from each other. This molecular motion we may readily change into the motion of masses, or motion in its most ordinary and palpable form. Heat, then, being a force capable of producing motion, and motion, as we have also seen, being capable of producing the other modes of force, it necessarily follows that heat is capable immediately of producing them. It will immediately produce electricity, as shown in the beautiful experiment of Seabeck. With regard to chemical affinity and magnetism, perhaps the only method by which, in strictness, the force of heat may be said to produce them, is through the medium of electricity; the thermo-electric current being capable of deflecting the magnet, of magnetizing iron, and exhibiting the other

magnetic effects; and also of forming and decomposing chemical compounds.

But investigation has gone still further. It is found that all these changes take place in rigorous accordance with the laws of quantity. As matter cannot be destroyed, neither is force capable of destruction; and as matter may be pursued through all its multitudinous changes without loss, the same principle is found to hold in regard to force. It has long been familiarly known that machines do not create force, but only communicate, distribute, and apply that which is imparted to them. In all cases the force expended is exactly measured by the resistance overcome. In the case of water-power, to lift a hammer of 100 pounds one foot high at least 100 pounds of water must fall through one foot; or, what is the same thing, 200 pounds must fall through half a foot, or 50 pounds through two feet. If a hammer weighing 1,000 pounds is employed with the same driving force, it will either be raised to only onetenth the height, or, tenfold the time will be required to raise it the same height. Thus in machines a certain amount of power acting as cause, produces an exactly equal amount of change, as effect.

It is precisely the same when the molecular forces are involved-those forces which involve the agency of atoms. It is well understood that a certain amount of fuel is necessary to perform a given amount of work with a steam engine. This means, strictly, that definite quantities of the chemical action of combustion give rise to a fixed quantity of heat, and this to a determinate quantity of mechanical effect. Dr. Faraday made the important discovery of the definite chemical effect of the voltaic current. He found that an equivalent of an element consumed in a battery gives rise to a definite quantity of electricity which will produce exactly an equivalent of chemical decomposition. For example, the consumption of 32 grains of zinc in the battery excites a current which will set free from combination 1 grain of hydrogen, 104 of lead, 108 of silver, 39 of potassium, and 316 of copper. But these are the combining numbers of those elements, and thus is established a remarkable equivalency between chemical and electrical forces.

That a certain amount of heat produces a definite quantity of mechanical force has been long known; but only lately has the question been inverted: how much heat is produced by a certain amount of mechanical force? The answer to this question gives rise to the science of thermodynamics. All friction, collision, and condensation, whether of solids, fluids, or gases, produce heat. But to ascertain at what rate mechanical force produces heat it requires certain standards of comparison known as the units of heat and force. The English unit of heat is one pound of water, raised through 1° F. The unit of force is one avoirdupois pound falling through one foot of space. By a great

number of experiments, Dr. Joule of Manches ter, Eng., demonstrated the mechanical equiv alent of heat-that is, how many units of force are equal to a unit of heat. He agitated water, mercury, and oil successively in suitable ves sels, by means of paddles driven by falling weights, and determined the exact amount of heat produced, and the force spent. By varied and repeated operations, conducted with consummate skill and great patience, he found that the same expenditure of power produced the same absolute amount of heat, whatever materials were used; and that a pound weight falling through 1 foot, and then arrested, would produce a unit of heat, that is sufficient to raise 1 lb. of water 1° F. The vast significance of this fact to science is obvious; every movement that takes place throughout the universe, whether of molecules or masses, has its fixed thermal value-it represents and may be converted into a definite amount of heat.

The imponderables, then, have passed away, with the epicycles of the old astronomers and the phlogiston of the old alchemists-monuments of the past progress of thought—and we have in their stead pure forces which are all varying modes of motion of ordinary matter. Science assumes the atomic constitution of matter; that there are interspaces between the atoms, and that these atoms are capable of va rious motions, and are probably in a state of constant movement. They may rapidly oscillate backward and forward, or whirl upon their axes, or even revolve through orbits, like what we may term the larger atoms of the solar system. Perhaps they execute several of these movements at the same time as do the planets. They are also believed to be endowed with polarities, and that their motions are subject to a polar control. Each molecular force is regarded as a mode of motion among the atoms; and as these motions may pass into each other the forces are convertible. Heat is that mode of motion among atoms by which they are caused to move further apart, producing expansion of the mass, or heating it. As the motion declines the body contracts and cools. Heat is produced by friction or collision because the mechanical motion which is arrested and disappears is changed to the molecular motion of the mass; while the mechanical motion produced by heat, as in the case of the steam-engine, is simply the consequence of the translation of atomic movement into massive motion. No force can be annihilated, and what the atoms lose, the mass gains.

Caloric, the electric fluid, and luminous cor puscles are denied; yet science still holds to the conception of a universal ether. Some writers, prominent among whom is Mr. Grove, protest against this as an inadmissible assumption. They say we can neither make nor prove the existence of a perfect vacuum, and, therefore, are not entitled to deny that matter is univer sal. There may be, and there probably is, matter, in some form, however attenuated,

everywhere; and, so long as there is a universal material vehicle for motion, the conception of a hypothetical ether is superfluous. But it is replied that, by the term ether, is meant this universal material, something capable of motion, and assumed to possess certain definite properties. Some such conception is necessary at the present time, in order to express those systems of movement in which the various forces consist.

As thermometric heat, or the heat of conduction, is a motion of the constituent atoms of bodies, so radiant heat, or that which darts forward rapidly in straight lines, is a movement of the ether. Light is no longer the shooting of corpuscular particles; it is a certain rate of undulation of the ethereal medium -it is motion. The different colors result from different rates of undulation. The va rious actinic, or chemical rays, are due to the same cause, and thus there is seen to be a close correlation between the radiant forces; they are all but modes of motion. The vibrations of the atoms may impart motion to the ether as it occurs in the radiation of every heated body; and, conversely, the undulations of the ether may be spent in setting the particles of bodies in motion, and thus bodies are warmed by radiation.

The most recent and important step in the progress of thermotic science has been made by Prof. Tyndall, and consists of an analysis of the relations of radiant heat to gaseous bodies, and especially to water vapor. We condense from the new edition of Youmans' Chemistry, in which the recent views are fully developed, a statement of the principles involved in this subject. An opaque body destroys the luminous waves which fall upon it; while a transparent one permits them to glide through between the atoms without interference. But there are bodies which destroy some of the waves and allow others to pass. If a piece of red glass be placed between the prism and the spectrum it stops the blue rays and transmits only the red-that is, it cuts down the more minute waves and gives passage only to the larger. If blue glass be used there is a reverse effect, the red rays being extinguished and the blue alone transmitted. Both glasses are transparent, yet, if placed together in the path of the rays, they are as opaque as a plate of iron, each destroying what the other transmits. This is also the case with the heat rays; they are of different kinds like the colors of light, and are arrested and transmitted differently by different substances. Rock salt is the most perfect diathermic body; that is, it allows all the heat rays, those from the sun and from the hand to pass through with equal freedom. Glass and a thin film of water will absorb or arrest the dark or obscure radiations, while they will pass luminous heat or those radiations which come from a luminous source. It is well known that the sunbeam is a bundle of heterogeneous radiations, and that the prism

spreads them out into a spectrum, thermal at one end, chemical at the other, and luminous in the centre. The same thing holds true of all sources of heat, luminous and obscurethey emit rays of different qualities. When the mixed rays from any source are passed through a plate, a certain portion of them is stopped, and another portion transmitted. But if the rays that are passed are made to fall upon a second similar plate, a much larger portion will be transmitted than went through the first the first plate sifted the ray, and the purified beam is better fitted to penetrate another similar plate. This principle explains the fact that glass readily transmits solar heat, while it stops the heat from a red-hot cannon ball in large quantities. The rays of the sun in coming through the atmosphere are strained of those rays which would be stopped by glass, so that the altered beam passes our windows without loss.

Tyndall's apparatus for investigating the influence of gases upon radiant heat, consisted of a long glass tube three inches in diameter, closed air tight at either end by caps of pure rock salt, and connected with apparatus so as to be exhausted and filled with various gases at pleasure. At one end of the tube was placed his source of heat, a blackened canister of hot water, and at the other end a thermo-electric pile-the most delicate instrument for measuring or detecting heat. By this machine, controlled so carefully as to secure the utmost precaution against error, Tyndall exposed various gaseous bodies to the dark thermal radiations. Purified air was found to arrest none or an exceedingly minute proportion of the rays; while pure oxygen, hydrogen, and nitrogen behave in a similar manner, being almost neutral. But when compound gases were introduced, there was a remarkable effect: olefiant gas, which is just as transparent as air, arrests 80 p. c. of the rays of heat. Pure transparent ammonia is still more impenetrable and stops the heat as light would be stopped if the cylinder were filled with ink. The same effect is produced if only a small proportion of these gases is mingled with the air of the cylinder.

In this manner, invisible gases become the means of sounding the atomic constitution of bodies. While heat rays pass through common oxygen without being intercepted, ozone, which is but another form of oxygen, arrests a large proportion of it like compound gases; we therefore infer that its atoms are arranged in groups or complex molecules. When aqueous vapor was introduced into the tube, it was found to be highly opaque to the dark radiations. Where the atmospheric gases arrest one ray of obscure heat, the small proportion of watery vapor contained in the air strikes down sixty or seventy rays. The consequences of this fact are in every way of the highest importance in the economy of nature. Luminous heat from the sun penetrates the air, and falling upon the

earth, is changed into obscure heat which is intercepted by the watery vapor of the atmosphere, and cannot therefore be radiated back again into space. The atmospheric vapor is therefore the means of maintaining the earth's temperature, and if it were withdrawn from the air, the loss of terrestrial heat would soon render the earth uninhabitable. In all those localities where the atmosphere is dry, the nightly loss of radiant heat is so great, that even in the burning desert of Sahara there is nocturnal freezing.

The aqueous vapor contained in the air exists mostly in its lower strata near the ground. The upper portions of the atmosphere are comparatively dry. Hence, high mountains being raised above the zone of watery vapor, are unprotected, and their heat consequently streams away into space with such rapidity that the temperature sinks to a low degree. As the winds dash against the frigid mountain peaks, their moisture is rapidly condensed and frozen into snow-hence the everlasting snow of these lofty land summits. In these circumstances, where the snow falls incessantly in large quantities, it is condensed into ice, and slowly creeps down the valleys in the form of vast rivers of ice known as glaciers. We thus see how the relations of radiant heat to aqueous vapor afford an explanation of the magnificent phenomena of snow peaks and glacial action. The ultimate cause of all these effects is of course that solar heat which originally changed the water into the vaporous form. The heat thus absorbed must again escape in condensation, while the grand function of the mountains appears as that of condensers. Each fragment of glacial ice is to be regarded as the product of the heat spent in first evaporating its water, and in this point of view the glaciers represent an amount of heat equal to five times their weight of melted cast iron. In connection with these important discoveries of the opacity of gases to radiant heat, Prof. T. Sterry Hunt has called attention to the effect which a large proportion of carbonic acid in the earth's ancient atmosphere must have had in preserving the high temperature of the earth.

The consummate series of investigations by which these results were reached, is admirably described by Dr. Tyndall, in his late work on heat, in which the new views of the nature of heat itself are applied with great skill and ingenuity to many of the phenomena of nature.

The history of the dynamical theory of heat is deeply interesting, as throwing a striking light on that action of the human mind which leads to great discoveries of the laws of nature. It illustrates, in a remarkable manner, that great truths are growths of time, and that discoveries oftener belong to epochs than to individuals. As far back as the time of Bacon, we find statements concerning heat which contradicted the common view, and which are susceptible of easy interpretation, in harmony with the recently established views. In the twen

tieth aphorism of the second book of the Novum Organon, its illustrious author remarks: "Now from this our first vintage, it follows that the form, or true definition of heat (heat, that is in relation to the universe, not simply in relation to man), is in a few words as fol lows: Heat is a motion, expansive, restrained, and acting in its strife upon the smaller particles of bodies, but the expansion is thus modified: while it expands all ways, it has at the same time an inclination upward. And the struggle in the particles is modified also; it is not sluggish, but hurried, and with violence." Again, the philosopher Locke remarks: "Heat is a very brisk agitation of the insensible parts of an object, which produces in us that sensation from which we denominate the object, but so that what in our sensations is heat, in the object is nothing but motion." But the first experimental step in this direction of thought, and perhaps the grandest step taken by any single mind, was made by an American, Benja min Thompson, afterward known as Count Rumford. He went to Europe in the time of the revolution, and devoting himself to scientific investigations, became the founder of the Royal Institution of England. He exploded the notion of caloric, demonstrated experimentally the conversion of mechanical force into heat, and arrived at quantitative results, which, considering the roughness of his experiments are remarkably near the established facts. He revolved a brass cannon against a steel borer by horse power, for two and a half hours, and generated heat enough to raise 184 lbs. of water from 60° to 212. In his paper read before the Royal Society, in 1798, he observes: "From the results of these computations, it appears that the quantity of heat produced equally in a continuous stream, if I may use the expression, by the friction of the blunt steel bar against the bottom of the hollow metallic cylinder, was greater than that produced in the combustion of nine wax candles, each of an inch in diam eter, all burning together with clear bright flames." Rumford explicitly announced the view now held of the nature of heat and wrote as follows, the italics being his own: "What is heat? Is there any such thing as an igneous fluid? Is there anything that with propriety can be called caloric? We have seen that a very considerable quantity of heat may be excited by the friction of two metallic surfaces, and given off in a constant stream or flux in all directions. Without interruption or intermission, and without any signs of diminution or exhaustion. In reasoning upon this circumstance, we must not forget that most remarkable circumstance, that the source of the heat generated by friction in these experiments, appeared to be inexhaustible. It is hardly neces sary to add that anything, which any insulated body or system of bodies can continue to furnish without limitation, cannot possibly be a material substance; and it appears to me to be extremely difficult, if not quite impossible, to