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LESSONS IN ARCHITECTURE.-XIX.

DOMESTIC ARCHITECTURE IN ENGLAND.-I. THE history of domestic architecture in our own country illustrates in a very striking manner the rise of civilisation and the extinction of barbarism. We have not to travel back more than a few hundred years to find domestic comfort a thing entirely unknown, and the abodes of princes entirely destitute of conveniences which are now considered necessary in the house of every peasant. Our Saxon forefathers lived in the rudest possible style. The homes even of kings and lords consisted simply of one large apartment or "hall," in which all the details of domestic life were carried on by themselves and their immediate attendants. Privacy was a thing entirely unknown. After the pursuits of the day-the chase or the fight -they assembled around one common board, taking place according to their rank in the household; and in the selfsame apartment all members of the household afterwards disposed themselves for sleep. It was only occasionally that one end of the common hall was separated from the rest by a screen, affording a rude retiring chamber for the lord and lady of the house, with a few privileged attendants.

tunity, amidst their constant warfare, for the culture of the arts of peace.

The Norman Conquest introduced little essential improvement. The residences of the great became imposing, from the necessity that they should be constructed for purposes of defence and security. Castles arose in all parts of the country; but

HADDON HALL (TUDOR STYLE, FIFTEENTH CENTURY).

Almost the only out-offices attached to the hall were the sheds or pens for the cattle and the swine. The dogs, more cherished, were allowed a place in a corner of the hall itself; and another corner was frequently occupied by the store of provisions. Sometimes, however, the latter would be placed in receptacles or cellars dug out under the hall. Its flooring was of earth, its walls of wood and clay, and its roof of thatch. For the admission of light, openings were left in the sides, and closed by wickerwork when night came on; for warmth, a log-fire was lighted in the centre of the apartment, and the smoke escaped by holes in the roof.

Such were the rude habitations of the higher classes of our ancestors before and even for some time after the Norman conquest. Domestic architecture, it will be seen, had as yet no existence in the land. The high civilisation of the Romans, who had been in the country nearly four hundred years, had failed to leave any

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they were built for warlike and not for domestic uses. So far as domestic arrangements are concerned, they could boast of little accommodation superior to that of the Saxon common hall. The abode of the residents was within the principal tower or keep, and this was usually divided into floors, each consisting of a single apartment. On the basement were the cellars and the dungeons; above, the entrance-hall, where stores were often kept; over that, the common hall, where the inmates cooked, feasted, and, for the most part, slept together; while the uppermost story was the dormitory of the lord and his guests. The door to this uncomfortable residence was on the second floor, and entered by stairs, which were raised and lowered at will, so that the edifice was inaccessible except to the inmates; the walls were pierced with but few openings to admit light, as these tended to weaken them against an enemy; and the roof was surrounded by a high crenellated parapet, from which defenders of the castle could fight against assailants below.

In keeps of larger dimensions, the floors were sometimes divided by a partition, and the additional apartments thus gained were used as council-chamber, chapel, etc.; but in no case was there anything approaching the modern idea of private apartments. Examples of these Norman keeps are found in that portion of the Tower of London

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permanent impress on the barbarous tribes which either inhabited or ravaged these islands in the following centuries. The Roman towns which had been founded in Britain, with their commodious buildings and stately villas, were razed and destroyed on the departure of the people who erected them. No existing models were in the land to tempt the aspirations of Saxon or Danish rulers to anything better than the practices of the barbaric North; nor, indeed, could they have found oppor

known as the White Tower, and in the castles of Rochester, Colchester, etc. The comparative immunity of the clergy from the strifes and the dan gers which compelled the nobles to regard their homes

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merely as warlike

posts and fortifications, led to the development of a more convenient plan of residence in monastic esta blishments. The

chief distinguishing characteristic

of these places, as far as domestic arrangement is conIcerned, was exhi bited in the addition of apartments and out-offices for the storage of provisions, cooking,

etc.; and it is to this source that we must look for the germ of the numerous and commodious offices which became attached to the mansions of the nobility at a much later date. In some few castles of the twelfth century we find indications of the separation of the culinary apartments from the common hall by partitions at one end; but these examples were exceptions to the general rule, and it was not until the thirteenth century that this degree of convenience became generally provided.

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In convenience of domestic arrangement, the castles of the lords progressed more slowly than the manor-houses dispersed through the country. The former were strongholds which at once overawed and protected the towns; the latter were the centres of rural occupation. Both belonged to the same proprietors, for the lord of a castle would possess perhaps several manor-houses in various parts of his estates, as the residences of his overseers and the granaries for his produce. Built at places less exposed than the towns to attack, these houses could often be erected with a greater regard to utility than to defence; and hence their arrangements in process of time became so far superior to those of the castle keeps, that the occupants of the latter would leave them, when they could, to sojourn for a time at a manor-house in the country. Thus becoming accustomed to greater domestic convenience, they desired, on their return, to introduce similar arrangements, as far as possible, within the castle walls; and in the thirteenth century, when a greater degree of peace and order began to prevail, we find that the nobles often erected buildings on the manorhouse plan within the castle enclosure. Besides this, they occasionally fortified the manor-houses after the castle manner, to adapt them to a more frequent and permanent residence than they could otherwise have made in them. The manor-houses, however, were still destitute of arrangements in accordance with our modern ideas of comfort and propriety. Their chief advan

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tage over the castles was in the possession, by gradual development, offices suited to the general range of domestic affairs. The addition of private apartments even for the chief members of the household was still almost unknown, as it was not yet required by the tastes and habits of a comparatively barbarous age. From this sketch of the abodes of the higher classes down to the close of the thirteenth century, an idea may be formed as to what was the condition of the lower. In the towns the citizens inhabited rude tenements of a single storey, built of wood and clay. In the country the

But we must confine ourselves in the present paper to the dwellings of the nobility and gentry, reserving the houses of the general population for consideration in another article.

Coming to the fourteenth century, we find a great advance in the general arrangements of the houses of the great. The erection of more commodious residences within the castle walls continued throughout this period. The disposition to combine convenience with strength was rapidly on the increase, and the growing submission of the barons to the authority of the laws favoured the arts of peace. But Architecture, as a science, found its chief scope in ecclesiastical buildings, and there was yet no foundation of settled style in the homes of the nobility. A great improvement in the accommodation was made by the addition to the presence-chambers of withdrawing apartments for the heads of the household, and it now, for the first time, became the practice to partition some of these apartments as bed-chambers. But the large hall was still put to its former uses, serving for the general mealroom of the residents, most of whom still slept upon its floor at night. The common hall was regarded as the most important part of the edifice. Its dimensions were imposing, its timber roof so highly ornamented in many cases, as to excite admiration at the present day. A splendid specimen of these ancient edifices exists in the Great Hall at Westminster; and another good example, attached to the house of a merchant prince at a later date than that now before us, is found in Crosby Hall, in the City of London.

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OSBORNE HOUSE (RURAL ITALIAN STYLE).

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EXAMPLE OF THE PALLADIAN STYLE.

people dwelt in sheds scarcely fit for the beasts of the field. And, although six centuries have elapsed since the period of which we have been writing, the latter remark is still true of the condition of the rural population in many parts of the country.

Among the minor improvements of the time must be mentioned the substitution of glazed windows for the open lattice throughout the various chambers, and the addition of hearths or fireplaces to these as well as the larger apartments. There was no attempt yet at regularity of ground-plan, but the common hall usually occupied the centre of the domestic buildings, the private apartments being placed at one end, and the kitchen and offices at the other.

In the fifteenth century we reach a transitional period, in which both

comfort and elegance began to be studied in domestic edifices. The wealth of the country was rapidly on the increase through its rising commerce, and the invention of gunpowder rendered castles and fortified houses comparatively

useless. The buildings of the fifteenth century, therefore, were characterised by a refinement previously unknown. The old manor-houses were transformed into mansions, and the castles, when not allowed to fall into ruin, became stately abodes. The exteriors were often handsomely embellished; the castellations, which had formerly a warlike use, now became a mere ornament; and the growing taste for privacy and comfort led to the gradual formation of a convenient plan for a wide range of apartments. We give an illustration of a portion of Haddon Hall, in Derbyshire, as one of the finest examples of the Tudor period, which embraces the latter part of the fifteenth and a portion of the sixteenth centuries. The general style is supposed to have been suggested by the Perpendicular Gothic, which was now in vogue in church architecture, and to this it will be found to bear many traces of resemblance.

At the beginning of the sixteenth century, ecclesiastical architecture was dying out, and vigorous attention began to be bestowed on the domestic architecture of the country. The middle of the century brings us to the Elizabethan age, when the nation had a long period of comparative repose, and was rapidly accumulating wealth. The power of the nobles had been greatly limited, and they no longer surrounded themselves by troops of retainers, who were sheltered and fed within castle and manor-house walls. In the reigns immediately preceding, these attendants had been gradually dispersed to engage themselves in peaceful arts, to the great advantage of the country. The residences of the nobility were now occupied entirely by themselves and their domestics; and, as a consequence of this progressive change, we find a total revolution in the domestic manners of the time, which produced a corresponding effect in domestic architecture. The large common hall, hitherto the most important feature in the abodes of the great, had fallen into insignificance as regards its actual uses. Additional chambers and private apartments were added, and English architects, some of whom had studied in Italy, devoted themselves to the convenient and harmonious arrangement of the whole. In Hatfield House, Hertfordshire, we have one of the finest examples of the style of the Elizabethan age, and its façade, or front, approached by a fine avenue of trees, forms one of our illustrations. Many other specimens of the substantial and commodious architecture of the period exist in various parts of the country, among which we may mention Longleat, Wilts, remodelled early in the present century by Sir Jeffrey Wyatt; Burleigh House; Charlton House, near Blackheath; and a part of Hampton Court.

The architecture of the Elizabethan age has been considered an attempt to combine the Italian style with the Tudor Gothic. The numerous perpendicular windows, the galleries and corridors, the ornamental gables or level balustrades which took the place of them, and the twisted chimney-shafts, are among its more conspicuous features; but its immense superiority over the building of preceding ages was shown chiefly in its commodious internal arrangements, which for the first time made the abode of a gentleman replete with comfort and convenience.

The interior of the mansion having now been entirely remodelled, its exterior shortly underwent another change, in the gradual adoption throughout England of the Italian style, by which the Tudor and Elizabethan were finally superseded. The Italian style was a revival of classic architecture, to which the works of Palladio were mainly instrumental, and hence it is frequently called the Palladian school. The term Cinque Cento is also applied to it, from its revival in Italy after the year 1500-cinque, fifth, being used as an abbreviation of fifteenth century. It was introduced into this country by Inigo Jones, and it soon became the fashion to adopt it. The peculiar features of this style were the range of classic columns used as a portico, and sometimes on each face of the edifice, which was square in form, and often surmounted by a cupola. In interior arrangements a change was made by allotting the ground floor, in large establishments, chiefly to the domestic offices, the dwelling-rooms and principal apartments being placed on the floor above, and over these the bed-chambers. A central saloon, the height of the entire building, took the place of the hall of former times, and was surrounded by the other apart

ments.

With various adaptations of this style to English taste, it continued in vogue throughout the seventeenth and eighteenth centuries. In the hands of many architects it lost its fairness

of proportion, and many of the square and ugly brick buildings of the last century can boast little in common with the Italian plan. In the present century Palladianism has declined, and a disposition has been shown to revert to old English forms in their best examples, and even to escape entirely from the thraldom of precedent, either in external or internal arrangement.

Italian architecture, however, in one or other of its forms and adaptations, still prevails to a considerable extent, although the purely classic system of Palladio has lost favour. The great club-houses in Pall-mall have all more or less of the style known as the Palatial Italian; and Bridgewater House, Piccadilly, the residence of the Earl of Ellesmere, is considered to be perhaps the most perfect example of this style in England. The Rural Italian, very similar in its details, but without the same uniformity of elevation-is also greatly in favour, and is especially adapted to picturesque situations. In this style the marine residence of Her Majesty at Osborne House was erected by the choice of the late Prince Consort, and an idea of its effect will be gathered from our illustration of a portion of that building.

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HAVING seen the mode of construction of the barometer, and the precautions which are taken to ensure its accurate reading, we must now see the way in which it is employed to foretell change in the weather, or to show the elevations of different places.

The barometer itself simply informs us what is the pressure exerted by the air at any time and place. This pressure is found to exhibit very great variations from time to time, and one of the causes of these is the moisture or dryness of the air. Moist air-that is, air charged with watery vapour-is found to weigh less than an equal bulk of dry air. This seems strange, but the barometer shows us that it is so; and we have a further proof of the fact if we observe the smoke from a chimney. On a fine day the air is heavy, and buoys it up in an almost straight line, while on a damp day it falls heavily. When, therefore, the air is charged with vapour, its pressure diminishes, and the barometer therefore falls. We have thus this general rule:When the barometer is low, wet or windy weather may be expected; and, on the contrary, when it is high, the weather wili not improbably be fine.

This rule, however, is very vague; and if taken by itself will often mislead. The words "much rain," "rain," "change," "fair," etc., usually inscribed on the dial of a wheel barometer, are also almost useless, as no correct inferences can be drawn from them, the actual height at which the barometer stands being a far less certain guide than the fact of the column being in a rising or falling state, as shown by the convexity or concavity of its surface.

There are three things which mainly affect the height of the mercury. These are

1. The force of the wind, which produces variations occasionally amounting to as much as two inches.

2. The amount of moisture in the air. The variations from this cause amount to about half an inch.

3. The direction of the wind; a north-east wind having a tendency to cause a rise, and a south-west wind a fall. These variations likewise amount to about half an inch.

From this it will be seen that wind affects the barometer much more than moisture does. It is important, then, to notice, together with the height of the barometer, the direction of the wind, and likewise the temperature at the time of taking the observation.

Space will not allow us here to give full instructions as to interpreting the barometer. We subjoin, however, a few general rules, and also the instructions drawn up by authority of the Board of Trade, and usually engraved on seamen's barometers. Those who require fuller rules should procure a small pamphlet called the "Barometer Manual," compiled by the late Admiral Fitzroy for the Board of Trade :

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A barometer, it should be borne in mind, shows what weather may be expected, and not what is present. A rising column usually indicates fair weather; a falling column, foul. In both cases, the more gradual the rise or fall, the longer continuance of the weather may be looked for.

Frequent fluctuations in the height are usually a sign of unsettled and changeable weather. A rapid rise also indicates unsettled weather, while a rapid fall frequently presages a storm. A high south-west wind nearly always causes the mercury to stand very low, even if no rain ensue; a north-east wind produces the contrary effect.

There are two corrections which have to be introduced into the readings of barometers if we would compare them with those of others at different places. The first is a correction for the height above the level of the sea at half tide. This is taken as the standard height; and it is clear that if the barometer is raised above this level, a portion of the atmosphere is left below it, and the pressure is therefore less by this amount.

It is found that an elevation of ninety feet cases a diminution in the height of the column of about of an inch, and this amount must therefore be added to the observed reading. This fact in itself shows how worthless the words on a weatherglass are, for in a valley it may stand at "fair," while on an elevation near by it points to "rain." The fact of its being on the ground floor or at the top story of a house is quite sufficient to alter the reading if the barometer be a good one.

The second correction that has to be made is for temperature. Mercury is very sensitive to heat, and expands considerably by it, thereby becoming lighter; a longer column will, therefore, be sustained by the pressure of the air. The difference caused by this is found to be about of an inch for every 10° above freezing-point, or 32°, and this amount must therefore be deducted from the observed reading.

Apart from the irregular fluctuations which we have been considering, there is a regular daily variation arising from tides in the atmosphere, for the aërial ocean, like the aqueous, has its periods of ebb and flow. The tides, however, are solar tides, being apparently caused rather by the heat of the sun than by its attraction of the air, and hence they occur at a regular time every day, and are always of one uniform height, the phenomena of spring and neap tides not being observed.

In temperate climates this fluctuation is but little noticed, as it only amounts to or of an inch, and is therefore hidden by the larger fluctuations before mentioned; if, however, we take the average of a continued series of hourly observations, we shall find that the daily maximum height is attained about nine o'clock in the morning, and the same hour in the evening, while the time of least elevation is about three o'clock.

In tropical regions the accidental variations of the barometer are very slight, as the wind and the moisture there are not subject to the variations they exhibit in temperate climates. Its fluctuations, therefore, occur with the utmost regularity, and range over about of an inch; and it is of little use there in foretelling the weather, except at rare intervals, when a sudden and great fall of the mercury is the precursor of a terrible storm or hurricane.

In many places daily registers are kept of the variations in the barometer, the wind, and the temperature, and careful observers are needed in other places, as, by comparison of such tables, many important meteorological questions may not improbably be solved. The height at noon is usually about the average of that during the day; if, therefore, only one observation can be taken, it should be at that hour; but if two observations can be taken, it is better, and then nine and three are about the most favourable times.

In observatories where it is required to keep a record of these variations, a self-registering apparatus is employed. This is usually adapted to a wheel barometer, the float being attached to the shorter end of a light and well-balanced lever. The longer end of this sometimes carries a pointer, which is caused

by clockwork to prick a hole at regular intervals in a ruled card, moved slowly under the point. The line joining these marks shows the changes in the height of the column.

Most mechanical arrangements for registering readings are, however, liable to get out of order, and have the disadvantage of marking the height at stated intervals only, instead of giving a continual line, and thus many minor variations are lost. The aid of photography has, therefore, been called in, and this difficulty obviated. The barometer is placed in a darkened room, and a small mirror is so arranged that it is turned by the rising and falling of the column. A small ray of light is admitted by an opening in a shutter, or, as is more commonly the case, the light of a powerful lamp is concentrated by a lens, and the ray of light from this falls on the mirror. A sheet of sensitised paper is so placed as to receive the reflected ray, and as this paper is slowly and evenly moved on by means of clockwork, a faint trace is left on it, which accurately shows every variation, however slight, in the height of a column. The trace on the paper can afterwards be developed and fixed, so that it may be kept as a permanent register of the varying pressure of the air. As the ray answers the purpose of a long lever without weight, variations of of an inch may be distinctly recorded in this way.

Having now seen something of the way in which the barometer is used as a weather-glass, we must just glance at the other important use to which it is applied, viz., as a means of ascertaining the elevations of mountains or other eminences. This was the first use to which it was put, and its indications in this respect are more to be depended on than in foretelling the weather. Pascal's celebrated experiment showed the principle, though he did not understand the mode of calculation.

If the atmosphere were of equal density throughout, there would be no difficulty whatever in the matter, for then the diminution in the length of the column of mercury supported would be exactly proportional to the elevation attained, and as we have already seen that an elevation of ninety feet causes a fall of about of an inch, we should merely have to allow 900 feet for every inch, and should thus ascertain the elevation.

This, however, is not the case, for every portion of the air is compressed by the weight of that above it, and thus the density diminishes rapidly as we ascend. It is usually reckoned that one-half of the entire atmosphere is passed at an elevation of a little less than three miles, though its extreme limit is supposed to be at an elevation of not less than forty-five or fifty miles, and perhaps more.

The exact calculation of height by means of the barometer is a rather complicated process, and involves higher branches of mathematics than we can well introduce here: the following simple rule will, however, give a very close approximation to the true height, especially if it be not greater than 5,000 or 6,000 feet:

Ascertain the height at which the barometer stands at the level from which the measurement is to be taken, and also note the reading at the highest point attained, the height will then be shown by the following rule of three sum:-As the sum of the two readings is to their difference, so 52,000 feet is to the height required. Suppose, for example, that the barometer at the level of the sea stands at 29-76 inches, and at the summit of the mountain at 26:18, we have the sum of the readings, or 29.76 +26-18 = 55'94, and their difference = 3.58, the equation will therefore stand thus:

As 55.94: 35:: 52,000: 3,327.

The height of the mountain is therefore 3,327 feet.

As, however, the temperature usually diminishes as we ascend, this will interfere a little with the result. We must therefore notice also the temperature at each place, and allow for the difference as before, by deducting from the reading at the level where the temperature is lower of an inch for every ten degrees difference in temperature.

If the weather be at all variable, or the ascent occupy a little time, it is far better to have another observer at the level of the ground, and thus let two simultaneous observations be taken, as all risk of variation is thus avoided.

As there is a difficulty in carrying an ordinary barometer from place to place, several special arrangements have been planned for the purpose. An ordinary cistern barometer is often employed, in which the cistern is attached firmly to the end of the tube, and made with leather sides, so that by turning the screw at the bottom, the tube is completely filled, and thus the risk of

breakage is much diminished. The tripod from which it hangs it will condense the vapour within, and the pressure being thus is also so constructed as to form a safe case for the instrument removed, ebullition will immediately commence again. This on the journey. experiment is a striking one, as the cold water has the effect of Still, even the best of these arrangements is heavy and awk-making that in the flask boil. ward to carry about, and therefore an entirely different kind of barometer is usually employed for this purpose.

Till recently, barometers containing liquid, whether mercury or water, were universally employed, but now dry or solid barometers are coming rapidly into use, on account of their much greater portability. These are called aneroid barometers, and consist of an exhausted chamber, the increase or diminution of the pressure on which causes a slight variation in its size, and the alteration being magnified by means of a series of levers, moves the hand over a graduated dial-plate.

In outward appearance the instrument closely resembles a watch, and some are now made no larger than this, and may therefore be easily and safely carried about in the pocket.

Having thus seen the effects of the pressure of the air, and the mode in which the barometer serves as a means of measuring it, we shall understand better the principle of the common pump, and why water cannot be raised by it to a greater height than about thirty feet. We shall also see the mode in which the pressure-gauge of an air-pump, shown at G in Fig. 2 (Vol. II., page 304), acts. It is simply a straight glass tube, dipping at the lower end into a cup of mercury, and communicating at its upper end with the exhaust pipe of the receiver. As the air is removed the mercury rises, and the difference between its height in this tube and that at which it stands in an ordinary barometer shows the amount of air left in the receiver. With a pump of the common description there is The first mode of making these was with a flat circular box, usually about one inch difference, but if it be very carefully made of some elastic metal, and having the flat sides corrugated, made, this may be reduced to less than half an inch, showing that to increase the elasticity. This pressed on one side against the less than of the original volume of air remains in the receiver. point of a screw, by means of which it could be adjusted so as to There is, however, another piece of apparatus, known as the correspond with the reading of a standard mercurial barometer. Sprengel pump, by which a much greater degree The other side of the case was pressed upon by a small pointer, of exhaustion may be obtained; and though it attached to the shorter end of a lever, which moved the hand. An is seldom if ever used to exhaust a large reimprovement on this form was, however, effected by M. Bourdon.ceiver, it is frequently employed in chemical He found that if a thin metallic tube be exhausted and curved researches, especially as it has the additional adinto a circular form, any increase of pressure on the outside vantage of rendering it easy to collect the air tends to curve it more, while a diminution of pressure straightens or gas removed from any vessel. The principle it. A flat tube is accordingly taken, and, having been ex- of this pump is very simple and yet very ingehausted and hermetically sealed, it is curved round into a cir- nious, a drop of mercury being made to take cular form. Fine wires or cords pass from the ends to a small the place of the piston in the ordinary pump. lever on the axis of the needle, and thus, when the pressure diminishes, the tube opens a little, drawing these wires, and thus moving the hand on the dial-plate to one side. A small spiral spring is also placed in the case, so that when the pressure again increases, and the wires are slackened by the tube curving, this may pull the hand back to its place.

The chief practical difficulty in the construction of this instrument arose from want of elasticity in the tube. If it could have been made of tempered steel it would have answered; this, however, was impracticable, but a flat spring placed inside the tube is found to answer nearly as well, and aneroid barometers can now be obtained so well made, that if they are occasionally adjusted by a standard barometer, they will serve for most purposes.

A new form of self-registering barometer has recently been brought out by M. Breguet, of Paris, in which three or four of the corrugated circular boxes are placed one above another, and the expansion of these moves a series of levers. At the further end of one of these is a pencil which traces a line on a cylinder driven by clockwork, and thus gives a continuous record of all changes in the pressure.

There is another plan of ascertaining heights, which may be mentioned here as being of easy application, and depending on the pressure of the air. It is by means of a thermometer. If we place a cup of warm water under the receiver of an air-pump and exhaust the air, we shall soon find the water rapidly boiling, even though its temperature is not higher than may be comfortably borne by the hand. When a liquid is exposed to a source of heat, the portions of it nearest the flame have a tendency to assume the state of vapour, and they do this as soon as their tension becomes equal to the pressure on the liquid. If, therefore, we diminish the pressure, a less tension will be required, and therefore ebullition will ensue at a lower temperature.

The temperature, then, at which ebullition ensues varies with the pressure, and hence is an indication of it just as the height of the column in the barometer is, and by means of tables constructed for the purpose we can tell the pressure from the temperature at which water boils, and thus deduce the height as before. As a rough guide, it may be stated that each 600 feet in elevation lowers the boiling point one degree on the Fahrenheit scale.

Another simple experiment, illustrating the fact of water boiling at a lower temperature if the pressure be diminished, can be easily tried. Procure a flask, and having partly filled it with water, place it over a lamp, and when the water is boiling, cork the flask tightly, and remove it from the lamp. The air has now been driven off, and if we pour cold water over the outside

The annexed diagram (Fig. 13) will show its construction and mode of action. A piece of stout glass tubing, A B, about five feet long, and having a bore about of an inch in diameter, is taken, and a funnel is fixed to the upper end. Usually it is melted on so as to form all into one piece. The lower end в is turned up a little. A glass stop-cock, c, is also fixed a little below the funnel, and a few inches lower another glass tube, D E, opens into A B. The tube or vessel to be exhausted is then fixed tightly to the end E. This may be done by a good piece of india-rubber tubing, if the joint be kept under water. The funnel is now filled with quicksilver, and a vessel is placed at в to catch all that runs down. The whole of the apparatus is usually fixed to a piece of board to guard against breakage.

B

Fig. 13.

E

The tap is now turned on, and the mercury, when it comes to D, is caused by the shape of the tube to fall in a series of drops, each of which acts as a piston, and carries down with it a portion of the air from E, and in this way a nearly perfect vacuum may be obtained. If a straight tube be fitted on E, the lower end of which dips into a cup of mercury, the mercury will rise in it till it stands at almost the same height as in a barometer placed by it. In fact, the difference in height is often almost imperceptible.

In order to collect the gas or air, the end в must dip into a vessel of mercury, and the gas will bubble up through it into a vessel placed to receive it, and may thus be saved for analysis.

LESSONS IN GERMAN.-XLV.

SECTION XCV.—IDIOMATIC PHRASES (continued). Werth (worth), like its equivalent in our language, is used in designating the value of things; as :-Dieses Pferd ist dreihundert Gulben werth, this horse is worth three hundred florins. When, however, the amount of one's wealth is referred to, some phrase like the following is employed:-Er hat ein Vermögen von zehn Tausend Gulden; or, Er hat zehn Tausend Gulden im Vermögen, he is worth ten thousand florins.

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