Provide a small flower-pot, the upper part of which is from six to seven inches in diameter; then with a circular rasp enlarge the aperture of its lower part, until it will just admit of the entrance of a cylindrical glass, two inches in diameter, and fifteen inches high, having a broad rest or foot at the base on which it may stand.. The glass should be so placed in the aperture that its brim may stand a quarter of an inch above the level of the upper edge of the flower-pot. A yard of broad tape must be wound round the part of the glass which protrudes from the lower part of the pot, and this should be coated with a thick covering of plaster of Paris, in such a way that the joint may be water-tight. Having put the apparatus aside for an hour, to allow the plaster to set, it may then be placed in the position shown in the diagram, with two bricks upon its base to keep it from danger of falling. Carefully fill the space in the flower-pot with the mixture of ice and snow described above, so that none of the mixture fall into the glass; afterwards pour water of ordinary temperature into the latter, till it is filled within an inch of the brim. In this experiment we apply the cold, as in nature, to the surface of the water, and we shall find that though the surface may freeze, the water below remains at 40 deg., or eight degrees higher than that at the surface. If a delicate thermometer be immersed in the glass, it would indicate, first, that the whole of the water was reduced by convection to 40 deg., but that the currents then ceased; and that, finally, while the surface was freezing, the lowest portions were never colder than 40 deg. Having attained its greatest density, the process of cooling is no longer extended to the whole bulk, but is confined to that portion only in immediate contact with the freezing mixture. If the apparatus be emptied, and its parts re-arranged, so that the freezing mixture shall be applied to the lowest portion of the glass, we shall find that the whole mass of water will be converted into ice, for the cooling below 40 deg. renders the water lighter; it ascends, while warmer particles descend, become cool, and in their turn re-ascend. Thus convection is established throughout the entire bulk of the water, and the whole of it is cooled down to freezing temperature, when it will become solid through its entire bulk. Though the heat of water, when boiling, varies considerably, in proportion to the density or rarity of the atmosphere-the freezing point remains always the same, and the chemist avails himself of this circumstance in the construction of the thermometer. The expansion of water, which has been described, is the cause of the bursting of pipes and closed vessels during winter. It is related, indeed, that cast-iron bombshells, thirteen inches in diameter and two inches in thickness, having been filled with water, and their fuse-holes firmly plugged with iron bolts, were burst asunder when exposed to the severe cold of a Canadian winter; thus demonstrating the enormous internal pressure to which they were subjected by the expansion of water in freezing. Herein we discover a most important agency, which produces great benefits to the husbandman. During the autumn and early winter months the soil receives into its interstices the water from the clouds, which creeps into every crevice in every clod; when frost comes, the water expanding, pushes the particles asunder, and breaks the lumps into crumbling mould. The water, too, which during the long year has been collecting in some hidden cavity of the rock, suddenly, under the influence of cold, assumes a giant power, and hurls the mass from the mountain sides. The flagstones and pavements are tilted up by the same mysterious power, and flakes of the ornamental plaster on our walls are pealed off. Ice has a great antiseptic power; that is to say, animal substances contained in it are prevented from decay. In 1803 the body of a mammoth-a race of animals now extinct-slowly appeared from a moun tain of ice, in which it had been preserved from decay for several thousand years; the flesh was in excellent preservation, however, and was eaten by bears, wolves, and dogs, with eagerness. During the winter, in the northern parts of Russia, meat is frozen and preserved in ice, and so sent to market in casks; and in Scotland salmon are packed in boxes with frozen water, which is an article of export from the lakes of North America. We will now proceed to speak of Snow; and first let us observe how beautiful and varied are the forms of its flakes, when thereof, and the heart is astonished at the raining of it." Snow is watery vapour suddenly frozen. Occasionally in Lapland the phenomena of the formation of snow is witnessed when the door of an apartment in which persons are assembled, is suddenly opened and a blast of cold air admitted, the watery vapour exhaled by their respiration being instantly frozen into flakes. Snow is a bad conductor of heat, or cold, and therefore acts as a most valuable covering for vegetables and seeds; wheat continues to grow beneath its covering, though every blade would be cut off if exposed to the frosty air. looked at through a magnifying glass, or microscope. How light and gracefully they fall, and how hilariously we greet the snow storm! "Through the hushed air the whitening shower descends, At first thin wavering; till at last the flakes With a continual flow. The cherished fields Put on their winter robe of purest white." How beautifully the naturalist of Scripture describes it too:-"As birds flying he scattereth the snow, and the falling down thereof is as the lighting of the grasshoppers, the eye marvelleth at the whiteness THE GUILLOTINE. THIS instrument derives its name from a Dr. Guillotin, a distinguished physician in Paris, and a person who embraced with ardour the cause of the revolution, and was elected one of the Deputies to the National Assembly. After it had been decided that crimes were personal, Guillotin proposed to substitute decapitation for other punishments, on the ground that, in the opinion of Frenchmen, that species of death did not attach infamy to the family of the criminal. The proposition was adopted: its author then pointed out a machine, which had been long known, as proper for the infliction of death, without giving any pain to the sufferer. Unfortunately for Guillotin, some wags gave his name to the machine, of which he was not the inventor, and which he had only brought into notice. Still more unfortunately, this machine became, in the hands of the ruffians who were masters of France during two years-the duration of which was equivalent to more than two centuries-the instrument of the most horrible vengeance, of the most odious crimes and Guillotin had a thousand times to grieve at seeing his name attached to the devastating axe with which the monsters had armed their executioners. After the termination of his political career, Guillotin resumed the functions of a physician, which it would have been better for his own repose if he had never quitted. He enjoyed, up to the last moments of his life, the esteem of all who knew him. Dr. Guillotin died on the 26th of May, 1814, aged seventy-six. HISTORIC TALE OF ANCIENT BRITAIN. THE solemn vision of past homes and ages, THE father of Avagus had fallen in battle, while defending his country from the Dobani, (comprising modern Gloucestershire and Oxfordshire), who, although driven back, succeeded in gaining possession of his eldest son, whom they carried, with several other prisoners, to their wild settlement, surrounded by dense forests and wide morasses. The lot of the youth was hard, and the toil to which he was subjected might have broken the spirits of very many who were yet inured to suffering, but the morning of life has few shadows, and with Avagus had been captured one Canobus, a savage of colossal form and strength, yet kindlyhearted, and who loved the son of his fallen chief with all the stern enthusiasm of his tribe. "Alas! poor youth," he would often say, "Why is it that when the giant oak has been uprooted, the young sapling must thus be torn away? Who may lift up thy head again, or sit beneath the shadow of thy spreading branches? No summer birds shall gather on thee, nor flocks lie down within thy shade at noon." Often, too, when his hard day's toil was ended, the strong man would wander forth, and explore the forest on all sides by moonlight; wishful to unravel its most secret windings, and ascertain the probable extent of those vast morasses which often crossed his path. He had been a close observer of way-side marks from early youth, and when ranging through his native woods in quest of game he never failed in readily finding his backward track, though to a less practised eye the mazes of the forest might have seemed interminable. When, therefore, the rising moon witnessed the going forth of Canobus, the first ruddy streak of dawn betokened his return to the hard couch-if such a bed of fern, within a cavernous recess, might be termed--whereon his young charge slept. That sleeping child, and the gaunt figure over which the winters of at least forty years had passed, tattooed from head to foot, and loosely clothed with a shaggy deer's skin, would have formed a subject of no small interest for a modern artist. But artists there were none in those stern days; for Britons had not then developed the glorious gifts that dwelt within them. Canobus wisely thought that the boy was too young and tender for a long and hazardous expedition through pathless woods and across deep rivers, he therefore continued to watch over his charge for nearly three long weary years, speaking to him, at times, of home, and keeping alive the memory of those who mourned him as dead. One day, however, when Canobus was keeping a few sheep in a distant clearing, and Avagus, by his master's orders, had collected a bundle of sticks, the savage suddenly broke silence:-" Boy," said he, "we have long dwelt in this wild place, and hard has been our lot; my heart has almost sunk within me for the want of space and gladdening sun-beams, and the sound of rushing streams, such as we felt and heard in our far-off land. You are now strong and active; the moon will be full this night-methinks your mother listens for your steps, and your brothers look forth across the plain. The forest is wide, and thickly tangled; wide marshes where rushes grow, and broad streams will bar our progress; but your steps are firm, and you early learned to swim the rapid torrents that rushed beside your hut. What say you, son of the chief your father-shall | we still remain forgotten of our tribe, or shall we not rather dare the forest and the flood?" The boy's eyes kindled with enthusiasm, his cheek glowed, and his heart beat tumultuously, but his words were few. Canobus had taught him the need of caution, and never, unless in the most perfect solitude, did the captives speak of home. That night, when all was still, and the natives of the wattled huts had laid down to rest, the boy and man were on their way. The moon had not then risen, but Canobus sought to leave his cavern while yet the night was dark, lest, perchance, his going forth might be observed, for a grassy area must be crossed before descending into the deep hollow ravine, with high banks on either side, that led into the forest. “Here then, we are," said Canobus, in a whisper to his companion," the moon will presently be up; meanwhile, let us hurry on, but take good care to hold fast by me, for if I lose you we cannot meet again.". The boy was stout of heart, but he felt the perils of his condition; and even when the beams of the full moon served to render every object clearly visible, he still clung to his guide. Silently and swiftly through the night went on the fugitives. Often did Avagus think within himself, Are we going right? And when some wild animal, roused from his sleep by the unwonted sound of their steps, started in his fright and rushed through the underwood, his young heart beat with apprehension. His fears were, however, groundless. Canobus had explored the secret recesses of the forest, with one single aim, for three long years; he had carefully noted every projecting mass of stone covered with variously tinted lichens, or old fantastic tree, streamlèt, or hollow way; and he knew exactly at what point the forest would be succeeded by a vast champaign country: pursuit, he thought, was utterly impossible, for the tribe had been engaged the day before in hunting, and every man had returned weary to his hut, loaded with game. When the morning dawned, and wakeful birds darted from the leafy coverts where they had passed the night, Canobus suddenly turned aside and began to ascend a rocky bank, covered with underwood, from thence into a gully, where grew majestic trees, with thick branches, and motioning the youth to follow him, he climbed up one of the most accessible, and having directed his companion to a hiding-place, between two large boughs, he bade him go to sleep. "We are safe here," he said, "I shall climb somewhat higher; you need not be afraid of my falling down, for I shall bind myself firmly to the trunk." Scarcely, however, had the wearied boy fallen asleep, when clouds began to gather on the horizon, at first resembling long pointed lines, spreading from east to west, then rapidly consolidating in murky forms, and presenting the appearance of innumerable undulations; presently the same clouds became mountainous, and filled the whole heavens; at which time a fierce wind arose, and howled through the forest, causing many a stately tree to sway beneath its fury, while the rain descended in torrents. Truly the mingled fury of the tempest was tremendous, with rain and wind, and flashes of red lightning, and the crashing of loud thunder; but the storm, however terrible, wrought good for those who bore its fury among the branches of the sheltering tree. They had crossed a wild brook, partly swiming and partly wading, and the stream, swollen by the heavy rain, which ceased not for at least two hours, rushed impetuously into the gully, and cut off all communication between the firm land and the group of trees in which the fugitives had taken shelter. About mid-day the clouds passed off, and the roll of distant thunder was heard at intervals; the sun broke forth and lighted up the dripping forest with inconceivable splendour, the birds renewed their songs, and the steaming woods appeared as if enwrapt in smoke. Avagus looked on the strife of waters that whirled and raged adown the gully, and was meditating on the possibility of gaining either of the banks; he called to Canobus, and began to question him, but instead of answering, the Briton slipt down warily, and motioned his charge to compress himself into the least possible space, while he darted up again with the celerity of a squirrel. Men who live much in the open air, whose faculties with regard to natural things are fully developed, hear voices at a great distance, and such was the case with Canobus. The storm had scarcely ceased when sounds far more appalling than those of the loudest thunders came remotely on his ear, with a certainty that rapid steps were pressing through the mazes of the forest. Presently the steps drew near, and loud shouts resounded on all sides, fierce dogs ran hither and thither, snuffing the ground as they went, and seeming to trace the onward progress of the fugitives, till stopping suddenly beside the torrent they lay down as if exhausted. "Here, then, they were, sure enough," exclaimed the chief, "and we need search no further; by this time they must have been carried headlong into the gulf below. Look," said he, "how the waters spin and whirl, no human power could withstand such force; their steps, no doubt, betrayed them in the darkness of the night and mid the rain. Well! we have lost two slaves who did good service; and had the prowling wolf attacked our sheep-fold earlier in the night, we could readily have overtaken them." Thus saying, the rough native of Dobani called to his dogs, and the whole company retraced their steps among the bushes. Canobus listened intently-his strained ear caught the faintest sound of their retreating voices and the breaking of underwood through which they passed, but as yet he neither spoke nor moved, for the sun was high in heaven, and he dreaded lest others of the tribe should have taken a different direction in search of him. It seemed as if some mountain stream had been loosened by the heavy rain, for the torrent already mentioned filled the gully to overflowing; it rushed down the ravine with terrible impetuosity, and Canobus could see clearly from his hiding-place the white crests of its foaming waters chasing one another with a strength and celerity that rendered all hope of escape by swimming impossible. The mind of Canobus was, however, fertile in expedients, and having carefully examined the wide-spreading branches of the tree, he found that some of the lower were intermingled with the boughs of one that stood contiguous, and these again, with others of equal strength and thickness; descending, therefore, to the place where Avagus lay concealed, he helped him from branch to branch, till having reached a majestic tree, whose giant trunk was rooted in dry land, he awaited the rising of the moon to set forward once more on his perilous career. Perilous indeed it was, for the vast forests that shaded the country of the Dobani were the haunts of wolves that prowled fearlessly in quest of prey; wild cattle overspread the open paths, and adders lurked among the grass. Yet still went on the wayfaring man and boy, through the dread lone forests and across vast tracts of open country, now breasting rapid torrents, and now walking warily amid vast quaking bogs, where small hillocks, if such they might be termed, overgrown with rushes, afforded safe stepping-places. And this, not for a few nights, but very many; while |