to which the muscle is attached, and in this way all the movements of the body are performed.

An uninterrupted supply of blood, and a connection with the brain by the nerves, are essential to the voluntary actions of the muscles. Thus, while the irritability which we have noticed is the proximate or efficient cause of muscular motion, the nerves may be regarded as its more remote or exciting causes. The passions act on the sensorium, which re-acts on the nerves of the heart; and thus the irritability of that organ is heightened, so as to cause palpitation and other irregular

movements.

The human body contains a surprising number of muscles. According to the calculation of anatomists, they nearly amount to four hundred and fifty. Their construction and collocation are wonderfully curious; and their utility is remarkably displayed in two endowments which they bestow upon us,-namely, the greatest agility of the whole body and of individual parts, and a great power of enduring continued exertions. These advantages arise partly from that perfection in the fabric of the muscles themselves, which, as well as the perfect state of the bones and joints, is most conspicuous in the adult stage of life; and partly from exercise and habit, the influence of which, in augmenting the extent and quickness of muscular motion, is most conspicuous in the feats of theatrical dancers, runners, boxers, and porters.

THE WONDERS OF HEAT.

Of the four elements which compose the world, fire is the most important and influential. The effects of heat are wonderful; it is the magic power which vivifies nature; and, if we cannot ascertain its original constitution or its precise mode of operation (which no philosophic inquirer has hitherto done), we may at least take notice of its properties.

Dr. Arnott says, "By observations made and recorded through by-gone ages, man has now come to know that the substances constituting the world around him, although appearing to differ in their nature almost to infinity, are yet all made up of a few simple elements variously combined; and he has dis

covered that the peculiar relations of these elements to heat,-as their being unequally expanded by it, and their undergoing fusion and vaporisation at different temperatures,-furnish him with ready means of separating, combining, and new-modifying them to serve most useful purposes. Where the primitive savage, looking around on rocks and soils, saw in their diversified aspect almost as little meaning as did the inferior animals which participated with him in the shelter of the wood or cave,-his son, with penetration sharpened by science, descries at once the treasures of the mine, and aided by heat, whose wonderful energies he has learned to control, pursues, through all the Protean disguises of ores and salts and solutions, each of the wished-for substances, until he secures it apart. For instance, in what to his forefathers for thousands of years appeared merely a red dross, he knows that there lies concealed the precious iron-king of metals! and soon forcing this in his ardent furnace to assume its metallic form, with imple ments made of it he afterwards moulds all other bodies to his will; the trees from the forest, and the rocks from the quarry, in obedience to these, come to be fashioned by him as if they were of soft clay, and at his command rise into the magnificent structures of palaces and ships, with which the earth is now beautified, and the ocean so thickly covered. The minute detail of the relations of particular substances to heat, forms a great part of the department of science called chemistry; but a general review of the subject will here suffice. The most common ores of metals are combinations of them with oxygen, carbonic acid, or sulphur, all of which are volatilised at much lower temperatures than the metals. Now simple roasting, as it is called, or strongly heating the ores, will often drive away great part of these adjuncts; and, where additional assistance is required, it is obtained by mixing with the ore something which, when heated, attracts the substance to be expelled more strongly than the metal does. Charcoal, for instance, heated with an oxyd ore, takes the oxygen, and, flying off with it as carbonic acid, leaves at the bottom of the furnace or crucible the vivified metal. Mercury, mixed with the dross of a mine, dissolves any particles of gold or of

silver existing in it, and the ingredients of the solution may afterwards be obtained separately by mere heating-the mercury passing away as vapor to where it is cooled and again condensed for repeated use, and the more fixed gold or silver remaining pure in its place,-just as in all other distillations, as that of spirit from wine, or of essential oils from water, there is the separation by heat of a more volatile substance. The only difference between what is called drying by heat and distilling, is, that in the one case the substance vaporised, being of no use, is allowed to escape or be dissipated in the atmosphere, while in the other, being the precious part, it is caught and condensed into the liquid form. A piece of cold charcoal lies in the air for any length of time without change; but, if heated to a certain degree, the mutual cohesion of its particles is so weakenedthat is, the particles are so repelled and separated from each other, that their attraction for the oxygen in the air around is allowed to operate, and they combine with that oxygen, so as to produce the phenomenon of combustion. The same is true, under similar circumstances, of almost any dry vegetable or animal substance, and of several of the metals. Nitre, sulphur, and charcoal, while cold, may be mixed most intimately without any change taking place; but, if the mixture, or any part of it, be heated to a certain degree, the whole explodes with extreme violence; for it is gunpowder. By the change of temperature, and the consequently-altered relative attractions of the different substances, a new che mical arrangement then takes place with the intense combustion and expansion, which constitute the explosion. Seasand and soda may be mixed, and even ground together, as completely as possible; but, if they remain cold, they remain also merely an opaque and useless powder: on heating the mixture, how ever, to diminish the cohesion of the particles of each substance to those of its own kind, so that the mutual attractions of the substances may come into play, they melt altogether, and unite chemically into the beautiful compound called glass; a product than which art has formed none more admirable; which in domestic use, for instance, is fashioned into the brilliant chandelier and lustreinto the sparkling furniture of the side

The same philosophical physician thus speaks of the apparent source of heat."Human art can gather the sunbeams together, and, by the intense heat produced in the focus of their meeting, furnishes another proof that the sun is the great source of heat. A pane of glass, or a small mirror, will reflect the sun's ray so as to offend an eye receiving it at a distance of miles as may be observed soon after the rising, or before the setting, of the sun, when his ray is nearly horizontal,-and the heat accompanies the ray: for, by many such mirrors directed toward one point, a combustible object placed there would be inflamed. Archimedes set fire to the Roman ships by sunbeams returned from many points to one, his godlike genius thus rivaling by natural means the supposed feats of fabled Jupiter with his thunderbolts. Again, when the light of a broad sunbeam is made by a convex glass or lens to converge to one point or focus, the concentrated heat is also there; for a piece of metal held in the focus drops like melting wax: and, if the glass be purposely moved, its focus will pierce through the most obdurate substances, as red-hot wire pierces through paper or wood. A hunter on his hill, and traveling hordes on the plains, often conveniently light their fires at the sun himself, by directing his energies through a burning glass. The direct ray of the sun, simply received into a box which is covered with glass to exclude the cold air, and is lined with charcoal or burned cork to absorb heat, and to prevent the escape of heat once received, will raise a thermometer in the box to the temperature of 230 degrees of Fahrenheit,-a temperature considerably above that of boiling water. And the experiment succeeds in any part of the earth, where there is a clear atmosphere, and where the sun attains considerable apparent altitude. We see therefore that a solar oven might in some cases be used.

"Reflecting on such facts, and on the globular form and the motions of our earth, we have a measure of the differences of climate and of season that should be found upon the earth. It is evident

verend sir,' said the king, with all due respect to your learning and conscience, perchance what you propose savours of severity. Not in the least,' returned the archbishop; 'such is the sentence I would give, if I were to be the judge upon the occasion. May all the saints bless you!' cried Henry; ere long I shall appeal to you.'

"On his return to the palace, Henry began to reflect upon some scheme which might deeply humiliate the delinquent nobles, and procure him ample reparation for his wrongs. From that moment he was confirmed in his previous resolution, of taking the reins of government into his own hands. He knew that he would soon complete his sixteenth year, and chose that moment to carry his plans into effect. With this determination he retired to rest. On the morrow he sent a formal invitation to his grandees, desiring them to assist in a grand entertainment, with which it was his intention to treat his noble and distinguished friends on his birth-day. After this he took no farther notice of the affair, but received the archbishop and the rest of the party in the usual manner; not the remotest suspicion existing among them that their unjustifiable conduct was known to the king. His birth-day at length arrived, and the grandees most joyfully attended the royal invitation; indeed, they were very eager to see what, entertainment could be prepared by the king, considering the indifferent state of his coffers. Perhaps a treasure had been discovered, or perhaps their lord had borrowed from the king of Arragon, or some other prince in Spain. But yet it puzzled Mendoza amazingly, how, if there was a treasure, it had escaped from his clutches; or, if a loan had been made, how his vigilance could have been eluded, to prevent his deriving any profit from the transaction. Henry had given circulation to various rumours concerning the splendour of the feast; and the nobles, leaving their surmises to be satisfied by the event, repaired to the palace on the wings of expectation. they gradually arrived, they were shewn into one of the chambers, where they were to wait until they were all assembled, and the doors of the banqueting-hall thrown open for their reception. The wished-for moment at length arrived. With much ceremony they were conducted to the saloon destined for the feast. But what was their amazement at the sight which

As

offered itself to their eyes? Instead of a decorated saloon, they found one which was almost tenantless from want, not only of ornament, but even of the most indispensable furniture. An unpolished deal table, and benches of the same material, were the only things in the room. The king himself, clad in complete armour, sat at the head of the homely board, which contained no food whatever, except a piece of hard coarse bread, and a jug of water for each of the guests. Henry, with much affability, desired the guests to take their seats, and to do justice to the fare he had prepared for them. They put on the best smiles they could command in so difficult a situation, and, sitting round the table, used their endeavours to push down their rebellious throats the hard and unsavoury food placed before them. They were puzzled to make out the meaning of this singular scene; but they had shrewdness enough to suspect that there was some mystery at the bottom. Again the good humour and affability of the king tempted them to imagine that the whole affair was a whim. Perhaps it was an exhibition emblematical of the self-denial and hard fare to which the ancient warriors had often been subjected; and indeed the armour in which Henry was equipped made the supposition probable. The king meantime devoured his portion of the food, in which he was rather well imitated by his guests, considering the very difficult nature of the task. I am afraid,' he then said, you have not found your repast to your satisfaction, but I hope you will relish the second course much better.' The announcement of a second course made the guests open their ears, and their eyes glistened with anticipation. They were confirmed in their surmises that the whole affair was a joke to give zest to the feast which was in store for them. Under this impression they rose up and followed the king, who now conducted them to another apartment, where the second course of the dinner was said to be laid out. They entered the place, when, lo! their couiftenances fell for the second time. Upon a view of the room it appeared that the joke was prolonged; and, indeed, if the thing were a joke at all, it must be confessed to have been one of a most unpleasant and serious description. The place was hung with black, the light of day shut out, and the gloomy glimmer of two or three lamps substituted for it. Awful emblems of death were also visible on every side;