participates with the boat in the double motion of rotation forces mutually neutralise each other's effects, and that conand translation in space, to which our globe is continually sequently the original state of the body is not affected. The subjected. In nature it appears, then, that we only recog-term equilibrium is used to designate this state of condition nise conditions of relative motion or relative rest. Inertia. Inertia is a purely negative quality of matter, and constitutes the well-known inability of matter to pass of itself from the state of rest to that of motion, or to modify the kind of motion with which it may have been impressed. If occasionally objects fall when left to themselves, this result is dependent upon the exercise of an attractive force, which draws them towards the centre of the earth, and not upon their own self-agency. If the velocity of a billiard ball on the table gradually diminishes, this result is attributable partly to the resistance of the atmospheric air, and partly to friction against the cover. It would be incorrect, then, to assume that the billiard ball holds within itself a tendency to rest rather than to continuance in motion, as certain philosophers of antiquity were in the habit of propounding, when they compared the natural tendency of matter to a lazy individual. In all cases where there is no resistance, continued motion proceeds without alteration, as we find exemplified in the course of the planets in their orbits around the sun. Application of the Preceding Deductions.-A great number of phenomena are explicable by the doctrine of the inertia of matter. For example, when one is desirous of leaping across a ditch, he takes a preliminary run, in order that at the instant when the spring is made the impetus generated by running may be superadded to that resulting from the spring itself. A person who alights from a carriage in motion participates in the motion of the carriage, and if the individual thus alighting does not take care to give his body an impression contrary in direction to that imparted by the carriage, he falls on touching the ground in the direction of the carriage. It is the quality of inertia which renders so terrible the accidents from concussion on railways. In fact, if the locomotive itself should be brought suddenly to a pause, all the train would continue its progress by reason of the force already acquired, and the carriages would be boken by striking against each Hammers, pestles, pile-drivers, &c., are all so many applications and illustrations of the principles of inertia; so in like manner are the fly-wheels of steam-engines, and the regulators of the motions of machinery. other. PRELIMINARY NOTIONS CONCERNING FORCE AND MOTION. Forces. By the term Force, is understood any cause capable of producing motion, or modifying motion when once produced. Thus, the muscular action of animals, weight, magnetic attraction and repulsion, and the tension of vapours, are all forces. In general the term powers is applied to designate those forces which tend to produce a certain effect; and the term resistance, to those forces opposed to the production of such effects. The former in consequence of their tendency to accelerate motion at each instant are called accelerating forces, whilst the general expression of retarding forces is applied to the latter ; yet the same force may be considered as a continually accelerating force at one time, and a continually retarding force at another time: for example, when a stone is allowed to fall from a state of rest, at some elevation above the ground, the action of gravity with which the earth, and indeed all matter, is endowed begins to affect the stone, and continuing to do so during the whole period of its fall, it reaches the ground with accelerated force; but if a stone be projected perpendicularly upwards from a place on the ground, its motion upwards will be continually retarded by the action of gravity during the whole period of its ascent, until it come to a momentary state of rest, and its progress upwards will be stopped. Gravity, when it acts in the manner described in the latter of these cases, is called a continually retarding force. Instantaneous and Continued Forces.-Forces are capable of acting upon bodies in one of two ways. First, during a very short period, as, for instance, that consequent on the shock or explosion of gunpowder; and second, those which continue to act during the whole duration of the motion, as gravity, and the traction of animals. The former are termed instantaneous, and the latter continued forces. in a body. Care must be taken not to confound the two states of equilibrium and rest. In the former state a body is submitted to the action of several mutually destructive forces; in the second a body is not acted on by any force. Nevertheless, it is a question whether there be any body actually at rest in the material universe. To this question we would answer in the negative. Characters, Unit, and Representation of Forces.-Every force is characterised-first, by. its point of application, that is to say, the point at which it immediately exerts its power; second, by its direction, that is to say, the straight line which it tends to describe at its point of application; third, by its intensity, or, in other words, its relation to some other force considered as unity. The force chosen as unity in any particular question is altogether arbitrary; but whatever may be the amount of traction or pressure developed by a force, inasmuch as a certain weight may be made or considered to produce the same effect, it is customary to refer forces to some unit of weight, and in this country the pound weight, or some multiple of it, is generally the unit. Thus a force is said to be equal to 20 pounds, if the pressure of 20 pounds can be substituted for the action of the force. From a study of the characters by which a force is determined, the force itself is completely known when its point of application, its direction, and its intensity are given. In order to represent the different elements of a force, we draw an indefinite straight line through its point of application, and in the direction along which it is exerted. Then upon this line some arbitrary unit of length is marked, commencing from the point of application, and extending in the direction of the force. This unit of length is then repeated as often as the given force contains the unit of force. As the consequence of this arrangement, we have a straight line which completely determines the force. In order to distinguish forces froni each other, they may be represented by letters, such as P, Q, R, placed upon the line indicating their several directions. In order to facilitate the understanding of many physical phenomena, it will be necessary to refer to certain principles which are demonstrated in mathematical treatises on natural philosophy. These principles will be cited in the next and subsequent articles. LESSONS IN GEOLOGY.-No. XLII. By THOMAS W. JENKYN, D.D., F.R.G.S., F.G.S., &c. CHAPTER III. ON THE INFLUENCE OF ATMOSPHERIC AGENTS ON THE SECTION VIII.-ON ICEBERGS. § ii. ON THE TRANSPORTING POWER OF DRIFTING ICEBERGS. In the lessons which were given you on the formation and agency of glaciers, you have learnt that all the rocky fragments, which glaciers brought down from the lofty ridges of the Alps, were deposited in a terminal moraine, and that, at some earlier epoch, they had left behind them on the sides and ledges of the mountain, at a much higher elevation than they reach in our day, enormous blocks of stone called boulders. For illustrations of this process, consult the diagrams in the Lessons on Glaciers. Boulders, like those on the flanks of hills in the Alps, are found in very extensive districts all over the north of Europe and America. Some of the blocks are waterworn, others are rugged and angular. They consist of fragments derived from rocks of all kinds and of all ages, primitive, volcanic, and fossiliferous. Many of them are of enormous dimensions, varying from three feet to several yards in diameter. In some cases, such a boulder deposit consists of blocks that have been severed and torn from the rock that lies immeEquilibrium.-When many forces are simultaneously operat-diately beneath them. In such circumstances the boulders are ing upon one and the same body, it may so happen that the of the colour and lithological character of the underlying strata red in a district of red sandstone, grey in one of shales, black | in one of coal, and white in one of chalk. Boulders of this description are easily accounted for. But all over Russia, Poland, Germany, Holland, England, Ireland, Canada and North America, broad plains and the sides of mountains have boulders strewed over them, for which there is no parent rock within scores and even hundreds of miles. Boulders and stony fragments of this description abound in England. They are frequently met with, in fields, half buried in the soil, and are often turned up by excavations in roadmaking and railway cutting. Whenever you see a boulder, it suggests to you two questions: first, where has it come from? and secondly, what brought it to the place it now occupies? Geologists have examined these two questions with much attention and skill, but they could find no satisfactory answers, before they adopted the hypothesis of the transporting power of drifting icebergs and packed ice. To interest you in the solution of these two questions, it is necessary to mention some of the most remarkable facts connected with this boulder deposit, or, as it has been called, the NORTHERN DRIFT. 1. There can be no doubt that all the boulders have come from the north; for their course, both in Europe and America, is found to be either due north and south, or varying a few degrees to north-west and south-east. The immense plains of Russia and Poland are covered with thousands of blocks of granite, all of which agree in mineralogical character with the mountains of Lapland and Finland. In Denmark, Holstein, now 100 feet above the level of the sea, in the Gulf of Bothnia. On the summit of this ridge lie scattered numerous large boulders of gneiss, in size from nine to sixteen feet in diameter. The sand on which the boulders rest is full of shells which now inhabit the Baltic sea. Hence, the boulders were brought thither after the Baltic was formed, and were transported across the waters of that sea. In Scotland, the Grampian Hills are from 3,000 to 4,000 feet high. To the south of these mountains lies the deep and wide valley of Strathmore. To the south of Strathmore are the Sidlaw Hills, composed of sandstone and shales. On the flanks of these hills, at an elevation of 1,500 feet above the sea, are found large blocks of mica schist, some of them three, some of them fifteen feet, in diameter. Blocks of precisely the same character are strewed in the intervening valley of Strathmore, all of which have come from the Grampians, fifteen miles from the Sidlaws. To the South of the Sidlaws are the Pentland Hills, about 1,100 feet above the sea. On one side of these hills there is a huge block of mica schist, from eight to ten tons in weight, which must have come from the Grampians fifty miles off, and which must have been borne over the Sidlaws about thirty miles distant. 3. The fragments which form these boulders have been removed to an immense distance from their parent rocks, or what geologists call rocks in situ. In the southern parts of Russia and Germany many of these boulders are found at the distance of 800 miles, and some even 1,000 miles, from the nearest rocks from which they could have been dislodged. and Pomerania, the sandy flats have, scattered over their whole extent, fragments of syenite, gneiss, and trap, exactly of the same description as the rocks of Sweden and Norway. Boulders, containing specimens of almost all known rocks, have been transported to the eastern counties of England. In Cambridgeshire, Huntingdonshire, Bedfordshire, Herts, Middlesex, Essex, Suffolk and Norfolk have been found fragments from Silurian rocks, carboniferous series, lias, oolite, chalk, trap, granite, and other crystalline rocks. Some of these boulders could have come only from Norway and Sweden, for Sir CHARLES LYELL traced them from those two countries to Denmark across the Elbe, through Westphalia, to the borders of Holland. "We need not," he says, "be surprised to find them reappear on our eastern coast, between the Tweed and the Thames,-regions not half so remote from Norway as are many Russian erratics from the source whence they came." On the western coast, and in the midland counties of England, similar facts are met with. On the coasts, in the plains, and on the sides of the hills, of Lancashire and Cheshire, and through Shropshire, Staffordshire, and Worcestershire, immense deposits of pebbles and a vast number of boulders are found scattered, which must have been transported thither from Cumberland and Dumfriesshire in Scotland. 2. Boulders have been transported across seas and lakes and plains, and over the ridges of high hills and mountains. Near Upsala, in Sweden, there is a ridge of sand and gravel that is Boulders from Scandinavia are found on the declivities of the Alps. Instances of similar extent of transportation abound among the boulders scattered over the northern districts of the United States of America. 4. The most remarkable and the most puzzling circumstance in this formation, is the fact, that some of these boulders have evidently been transported from a lower to a higher level. Near Kirby Lonsdale, there are many large blocks of grauwacke scattered over the mountain limestone at an elevation of from 50 to 100 feet above the parent rock, and even almost to the top of the Fell, 500 feet above their original position. In that district there is another case in which boulders have been transported from the Vale of Eden, where the parent rock is 500 feet above the sea, to and over the pass of Stainmoor, at the height of 1,400 feet, so that these boulders lie now 900 feet above the level of the rock in situ. Similar facts are found on Ben Erin on the western side of Glen Roy, on Arthur's Seat near Edinburgh, in the Isle of Man, and in North America. One of the most singular facts connected with the elevated position of boulders occurs in North Wales. As the traveller journeys westward on the Holyhead Road, he comes to Llyn Ogwen, and on his left rises a precipitous mountain called Moel Tryfaen, which attains the height of 1,392 feet above the level of the sea. On the summit of this rock are found chalk flints associated with bilders of various kinds. There is good reason to believe that the chalk flints were transported from Ireland, and therefore from a considerably lower level. Facts of this description form one class of the difficulties which press upon the theory of icebergs as the agents of transportation; for no floating ice could possibly transport boulders from a lower to a higher level. Mr. Darwin ascribes these results to the joint action of floating icebergs and of packed coast ice. He shows that on Moel Tryfaen the well-rounded pebbles of chalk flints and other boulders were, in all probability, transported by coast ice, though it is at the same time evident, from the extraordinary manner in which the lamina of the slate rocks have there been shattered, that icebergs have also been driven against them when under water; so that both actions seem to have concurred in that neighbourhood. You have now been informed of the remarkable positions of distance and elevation in which boulders are discovered. Our next business is to try to answer the question,-how they came there? The most skilful geologists found it almost impossible to account for the position of boulders, before they adopted the glacial, or rather the iceberg theory, called also the glacio denly. This is proved from the general absence of organia remains in the clays and sands, which are found to cover the formation of the drift boulders, and from the complete preservation of the flesh and the hair of the elephants which were discovered in the frozen mud of Siberia. 4. This great and sudden reduction of the temperature would fill the glens of the Polar mountains with immense glaciers, which, as explained in our last lesson, would stretch far into the waters of the Northern Sea. Even at the present day, many of the glaciers that descend the ravines of Spiztbergen project several hundred feet from the coast into the sea. Indeed, at this epoch, called the glacial period, it is probable that northern mountains of comparatively moderate height would have their valleys filled with glaciers, and that vast sheets of ice would stretch eastward, and westward, and southward, as far as the phenomena of boulders have been observed. 5. In other circumstances the icebergs detached from these glaciers that protruded into the Polar seas, would take up and convey to a distance huge masses of rock, which water alone, however impetuous, could never have moved, and would transport them hundreds of miles without wearing off the angularity oftheir edges. 6. As the lower surface of the icebergs would either be abraded by the action of the sea, or melted by the increased temperature in the south, the masses of clays, sands, gravels, and boulders, which they had brought down as glaciers, or imbedded as coast-ice, would drop down and be scattered at random over the bottom of the sea. 7. The bottom of this sea might be extensive plains, or high ridges of hills. When you consider that seven parts out of nearest to the vera causa, or the real agency that produced the result. 1. It is certain that all the boulders come from the north. All the rocks, of which boulders are specimens, are in situ towards the north. All the shells which are frequently found in the clays associated with the boulders indicate a northern climate. There seems also an intimate connexion between a .very cold or extreme northern climate, and the various geological appearances which have been called glacial. 2. In the neighbourhood of the Baltic, the course of the erratic blocks, and the grooving and the smoothing of rocks, have been traced from the level of the sea shore to elevations of above 3,000 feet. Nothing of this kind has been found either on the shores or on the sides of the rocks above the Mediterranean, nor in the equatorial parts of Asia, Africa, and America. 3. It can be proved that at an earlier age in the history of our globe, at the close of the tertiary period, the northern hemisphere was considerably colder than it is at present, and that this diminution in the temperature took place very sud eight of a high iceberg are under water, it is obvious that such a deep body of ice, in moving southward, would strike against the crests or the flanks of these submarine ridges, and there deposit its clays and boulders. These submarine hills became, at another geological period, elevated, by volcanic acticn, to an elevation much higher than the sea, and bearing on their ridges or sides the boulders that had been imbedded in their surface of clay or sand. 8. The application of the iceberg theory to the elucidation of boulder phenomena is in full harmony with all that science has taught us about glaciers. What we know of terminal moraines corresponds with the accumulations of clay and gravel which are called the Drift, and which are found associated with the blocks or boulders. It also accounts for the smoothing and grooving of rocks, for the parallelisms in the markings or striæ on the surface of rocks, and for the high and precipitous ledges on which the boulders have been lodged. Boulder phenomena, however, present three difficulties which the iceberg hypothesis does not seem to obviate. First, boulders are frequently found water-worn and rounded at the subsiding. As it gradually subsides, the coast-ice would, by the first powerful gale, be driven still higher up, and thus, as the subsidence continued and the gales repeated, the boulders would be impelled onwards and upwards. When this land would again emerge and appear above the waves, the boulders on its sides or ledges would lie far above the neighbouring rock from which they were derived. edges, a result which would not be produced by transportal Now, imagine such a coast, 80 covered with boulders, to be in icebergs. Secondly, the size of the boulders, as a general rule, diminishes as their course is traced southward, whereas an iceberg would easily have carried a block of twenty tons as far as a boulder of twenty pounds. Thirdly, floating icebergs could not have placed boulders on elevations many hundred feet higher than the rocks from which they are derived. To enable the iceberg hypothesis to meet these difficulties, Mr. Darwin has brought to its aid the agency of coast-ice, and especially the action which is called the packing of the ice, as witnessed in high latitudes. 1. It is possible that such boulders might have been worn and rounded while they were in charge of glaciers in polar valleys, and worn in their progress towards the coast, before they came far enough to form the constituents of an iceberg. The coast-ice, however, that is formed on shallow shores, even where no glaciers protrude, will take up and enclose the stones and pebbles that lie along the coast. When the ice melts, they drop, and the next winter's ice takes them up again. Or the coast-ice that imbeds them may strand them with violence on a different part of the shore; and such ice may become detached icefloes, which carry these fragments over rocky shoals, and thus wear and polish them. As such coast-ice is not very thick, it is likely to be landed in shallow places: then, by the action called the packing of the ice, the pebbles and boulders imbedded in it will be driven up the beach, and will eventually be left perched on ledges of rock. On the supposition that such a coast would become submerged and again rise above the sea, it might be expected that boulders, which§ had thus been buoyed up by coast-ice during long-continued ages, would be well rounded. 2. The gradual decrease in the size of the boulders, the further we proceed from the parent-rocks, does not always hold good. Mr. Darwin says, that on the plains of Patagonia, the two largest boulders that he saw were near the outskirts of the deposit. When boulders are transported in sheets of ice, or fragments of coast-ice, called icefloes, the buoying and transporting agent is not of disproportionate power to its burden. As the icefloe decays, the heaviest fragments would naturally be apt to drop out first. The accounts of navigators intimate that the larger boulders taken up by coast-ice are, during some winters, not moved at all, while the smaller ones are drifting onwards. Hence the boulders that have travelled farthest, would, from having been repeatedly stranded every summer, be most worn, and therefore would be smaller than those which had travelled a shorter distance. The iceberg theory is itself almost sufficient to account for this sorting of the boulders. Icebergs float in a sea of variable depth. The heavier boulders require larger icebergs to buoy them up. The greater the volume of the iceberg, the sooner would it, in its southward course, strike against the shallower parts of the sea bottom, and deposit its clays and blocks; but the smaller and lighter icefloes, laden with finer gravel and smaller boulders, would pass over to a much greater dis tance. 3. As to the transportal of boulders from a lower to a higher level, it is not supposed that this takes place universally, but only in certain favourable situations, and which may be accounted for by the action called the "packing" of icefloes. Voyagers who have navigated polar regions have stated that the pack-ice frequently piles up and leaves blocks of stone at the height of thirty feet above high water-mark. In accounting for the erratic boulders and grooved rocks of Canada and North America, Sir CHARLES LYELL supposes that the land thus circumstanced first subsided gradually into the sea, and then, by an agency from below, emerged and attained a higher level than before. While it was in the process of sinking, the sea that then bordered it was covered with ice. bergs floating from the north. As these bergs grounded on the shallow bottoms, or the sides of ridges in the sea, the force that propelled them pushed along also materials of sand, gravel, and pebbles, which then lay at the bottom of the sea. By the combined forces of the current and of the iceberg, the rugged and angular blocks which were embedded in the lower surface of the iceberg, and which projected out of it, would have the power of marking or grooving the underlaying rocks, by which action the blocks themselves would become worn and rounded. Sir RODERIC MURCHISON, in his "Geology of Russia," has thrown considerable light upon the boulder and drift deposits. He thinks that when the granitic rocks of Norway and Sweden, &c., were emerging from the ocean, their rugged pinnacles were shattered into huge fragments by the expansive power of the severe frost of the period. Glaciers carried these enormous masses to the sea-coast, whence they were taken up by icefloes, which, by the force of subaqueous currents, transported them hundreds of miles to the south, and then deposited them on the sea bottom. These submarine deposits were, in a subsequent period, upheaved above the ocean to form the districts which are now called Russia and Germany, where the boulders deposited by icebergs are the monuments of the change by which the bottom of the sea became dry land. LESSONS IN FRENCH.—No. LXXIX. Accuser (s'), to accuse one's self Abstenir (s'), to abstain Achever, to finish Affecter, to affect Agir (s'), unip., to be the question Aviser (s'), to bethink one's self Avoir besoin, to want Avoir envie, to wish Avoir tort, to be wrong Brûler, to wish ardently Chagriner (se), to grieve one's self Commander, to command Défendre, to forbid Dépêcher (se), to hasten (se), (se), to leave off espérer, to despair Désoler (se), to grieve Efforcer (s), to endeavour Empêcher, to prevent Empresser (s), to hasten Epouvanter (s'), to be frightened Entreprendre, to undertake Enrager, to be vexed Etonner (s'), to wonder Excuser (s'), to excuse one's self Féliciter, to congratulate Feindre, to jeign Flatter (se), to flatter one's selj Frémir, to shudder Garder (se), to take care Gémir, to lament Glorifier (se), to pride one's self Hasarder (se), to venture Indigner (s'), to be indignant Ingérer (s), to take into one's head Jurer, to swear Méditer, to think, to intend Mêler (se), to meddle Menacer, to threaten Mériter, to deserve Moquer (se), to laugh at Mourir (figu.), to long Négliger, to neglect Pardonner, to excuse Plaindre (se), to complain Prendre garde, to take care, heed Prendre soin, to take care Presser (se), to hasten Présumer, to presume Promettre, to promise Rebuter (se), to be weary Il vaut mieux hasarder de saurer un coupable que de condamner un innocent. VOLTAIRE. Le monde se vante de faire des heureux. MASSILLON. § 133.-RULE. (1.) Two or more verbs may govern the same object, provided they require the same regimen : et nous louons nos enfants. We love, we instruct, and we Nous aimons, nous instruisons, praise our children. This sentence is correct, because aimer, instruire, and louer, being active verbs, govern one and the same case, the direct regimen, (2.) But when the verbs require different regimens, they cannot govern one and the same noun; and therefore another form must be given to the sentence. We could not say in French,-Un grande nombre de vaisseaux entrent et sortent de oe port tous les mois,-A great number of vessels enter and go out of this port every month, because the verb entrer reaches its regimen by means of the preposition dans, and sortier by means of the preposition de. We should say : Un grand nombre de vaisseaux A large number of vessels enter entrent dans ce port et en sortent this port and leave it every month. tous les mois. See § 92, (1.) (2.), also note, and § 140. § 134. THE PARTICIPLE PAST. CORRESPONDENCE. [We insert the following remarks "On Bathing when heated," because we think them well worthy the attention of those of our readers who are fond of this exercise. Of course, we do not commit ourselves entirely to the accuracy of every point, because we have not had sufficient personal experience; but we consider that there is much truth in what our correspondent says.] ON BATHING WHEN HEATED. Sir,-At the end of the article on Physical Education which has reference to bathing in your No. for August 27th, you place certain rules to be attended to by the bather before going into the water. I am well aware that it has been long a popular as well as profes sional axiom that sudden vicissitudes of temperature are dangerous, that a previous hot state of body augments the hurtful effects of cold however applied; but the proposition thus broadly stated is not universally true. The inhabitants of Russia are in the habit, while reeking from vapour baths, of immediately rolling in the snow, or plunging into cold water without suffering from the change. Captain Scoresby, while in the Arctic Regions, often passed from his room where the temperature was from 55° to 60° to the mast head, where it was only 10°, without receiving any injury or inconve nience; and other instances may be brought forward. Thus it is plain that the proposition which assigns danger to extreme vicissi tudes of temperature requires some limitation; the effect of a sudden descent from one point to another in the scale of temperature, varies according to the state of the body at the time. Man, together with the warm-blooded animals, you are aware, by the faculty of evolving heat, maintain the same degree of inward temperature under very different degrees of outward temperature. Now if this power of evolving heat be entire, active and persistent, no peril need attend even violent alterations of external temperature. Unusual heat of the body at the time when the cold is applied, so far from implying danger, is really the condition of safety, provided The sword is blunted; the piles that heat is steady and permanent; but if a person be exhausted are extinguished. (1.) We have seen [§ 66, (3.)] that the participle past, not accompanied by an auxiliary, assumes the gender and number of the noun which it qualifies :Les inimitiés sourdes et cachees sont plus à craindre que les haines ouvertes et déclarées. NOËL. Quiet and concealed enmity is more to be feared than open and de clared hatred. (2.) The participle past accompanied by the auxiliary être, agrees in gender and number with the subject of the verb, whether the subject be placed before or after it. [See 135, (1.)] Humble virtue is often despised. The Greeks were persuaded, that the soul is immortal. When he perceived the urn in which were enclosed the ashes of Hippias, he shed a torrent of tears. and weakened by exercise, rapidly parting with his heat, if he remains at rest after and during the application of cold, then it is highly perilous, and likely to produce mischief. Thus cold is dangerous not when the body is hot, but when the body is cooling after having been heated. Thus those whose business it is to advise, may caution the public against the common mistake which has had its origin in the unqualified credit given to the maxim, that sudden vicissitudes of external temperature and exposure to cold while the body is hot are dangerous, whereas they are only dangerous under certain circumstances. Thus wet feet or a wet skin need cause no apprehension, so that active exercise is con tinued; but when that exercise ends, then it is that a change of clothes and a further avoidance of the application of cold is impor tant. You may safely tell the bather, that after walking on a hot day to the river's side, he had better not wait to cool himself a little before he plunges into the stream. The point to be remembered is that the heat which is preternaturally accumulated by exercise is held with little tenacity, is dissipated by profuse perspiration, and is speedy lost when to this perspiration is added a state of rest |