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ing, the moisture of the mortar; and this, if used plentifully, will consequently exercise a greater cementing # power; because from their contain-ing a larger portion of moisture, E the wall will not, of course, dry so soon as otherwise; and as soon as the moisture is absorbed by the #: pores of the stones from the mor-£ tar, the lime, losing its power, leaves | the sand, so that the stones no longer £ adhere to it, and in a short time the work becomes unsound. We may £ see this in several monuments about : the city (Rome) which have been built of marble, or of stones squared externally, that is, on one face, but filled up with rubble run with mortar. Time in these has taken up the moisture of the mortar, and destroyed its efficacy by the porosity of the surface on which it acted. All cohesion is thus ruined, and the walls fall to decay. He who is desirous that this may not happen to his work should build his two-face walls two feet thick, either of red stone, or of bricks, or of common flint, binding them together with iron cramps run with lead, and duly preserving the middle space or cavity. The materials in this case not being thrown in at random, but the work well brought up on the beds, the upright joints properly arranged, and the face-walls, moreover, regularly tied together, they are not liable to bulge, nor be otherwise disfigured. In these respects one cannot refrain from admiring the walls of the Greeks. They make no use of soft stone in their buildings; when, however, they do not employ squared stones, they use either flint or hard stone, and, as though building with brick, they cross or break the upright joints, and thus produce the most durable work. There are two sorts of this species of work, one called isodomum (CC), the other pseudisodomum (DD). The first is so called, because in it all the courses are of an equal height; the latter received its name from the unequal heights of the courses. Both these methods make sound work; first, because the stones are hard and solid, and therefore unable to absorb the moisture of the mortar, which is thus preserved to the longest period; secondly, because the beds being smooth and level, the mortar does not escape; and the wall, moreover, bonded throughout its whole thickness, becomes eternal. There is still another method, which is called eurXextov (emplectum) (E), in use even among our country workmen. In this species the faces are wrought. The other stones are, without working, deposited in the cavity between the two faces, and bedded in mortar as the wall is carried up. But the workmen, for the sake of despatch, carry up these casing walls, and then tumble in the rubble between them, so that there are thus three distinct thicknesses, namely, the two sides or facings, and the filling in. The Greeks, however, pursue a different course, laying the stones flat, and breaking the vertical joints; neither do they fill in the middle at random, but, by means of bond stones, make the wall solid, and of one thickness or piece. They moreover cross the wall from one face to the other, with bond stones of a single piece, which they call 5uatovol (diatoni) (F), tending greatly to strengthen the work.” We have preferred to give this account in the words of the author himself as the best description, because that of a practical architect, and though capable of some abbreviation, not sufficiently so to justify our own alteration. Mass. (Germ. Masse.) The quantity of matter whereof any body is composed. The mass of a body is directly as the product of its volume into its density. Multiplied into the constant force of gravity, the mass constitutes the weight; hence the mass of a body is properly estimated by its weight. MAstic. (Gr. Magtikm, a species of gum.) A cement of recent introduction into England, employed for plastering walls. It is used with a considerable portion of linseed oil, and sets hard in a few days. From this latter circumstance, and from its being fit for the reception of paint in a very short period, it is extremely useful in works where expedition is necessary. MAsuccio. See ARchitects, list of 124. MATERIALs. (Lat. Materies.) Things composed of matter, or possessing its fundamental properties. Those used in building form the subject of the second Chapter of the second Book of this work, to which the reader is referred. MATHENA rics, (Gr. Madnois, learning.) The science which investigates the consequences logically deducible from any given or admitted relations between magnitude or numbers.

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It has usually been divided into two parts, pure and mired. The first is that in which geometrical magnitude or numbers are the subjects of investigation; the last, that in which the deductions so made are from relations obtained by observation and experiment from the phenomena of material nature. This is sometimes called physics, or physical science. On the subject of mathematics, the reader is referred, as respects what is necessary for the architect, to ARITHMEric, and ALGEBRA, and GeoMETRY, in the body of the work, Book II. Chap. I. Sects. 1 and 2. MATTER. (Lat. Materies.) That which constitutes substance. Of its intimate nature, the human faculty possesses no cognisance, nor either by observation or experiment can data be furnished whereon to found an investigation of it. All that we seem likely to know of it is its sensible properties, some whereof are the foundation of physical science, others of the different subordinate sciences. MAURIrius. See ARchitects, list of 86. Mausoleum. A term used to denote a sepulchral building, and so called from a very celebrated one erected to the memory of Mausolus, king of Caria, by his wife Artemisia, about 353 B. c. From its extraordinary magnificence, the building just mentioned was in ancient times esteemed the seventh wonder of the world. According to the account of Pliny, it was 111 feet in circumference, and 140 feet high. It is said to have been encompassed by thirty-six columns, and to have been much enriched with sculpture. MEAN. In mathematics, that quantity which has an intermediate value between several others, formed according to any assigned law of succession. Thus, an arithmetical mean of several quantities is merely the average, found by dividing the sum of all the quantities by their number. A geometrical mean between two quantities, or a mean proportional, is the middle term of a duplicate ratio, or continued proportion of three terms; that is, that the first given term is to the quantity sought as that quantity is to the other given term. In arithmetic it is the square root of the product of the two given terms. The harmonical mean is a number such that the first and third terms being given, the first is to the third as the difference of the first and second is to the difference of the second and third. MEAsURE. (Lat. Mensura.) In geometry, strictly a magnitude or quantity taken as a unit, by which other magnitudes or quantities are measured. It is defined by Euclid as that which, by repetition, becomes equal to the quantity measured. Thus, in arithmetic, the measure of a number is some other number which divides it without a remainder, though, perhaps, such a definition rather intimates the notion of aliquot parts. But that meaning on which this article is submitted is the unit or standard by which extension is to be measured. We have measures of length, of superficies, and of volume or capacity. But the two latter are always deducible from the former; whence it is only necessary to establish one unit, namely, a standard of length. The choice of such a standard, definite and invariable, though beset with many and great difficulties, modern science has accomplished. The rude measures of our ancestors, such as the foot, the cubit, the span, the fathom, the barleycorn, the hair's breadth, are not now to be mentioned in matters of science, much more precise standards having been found, and not susceptible of casual variation. Nature affords two or three elements, which, with the aid of science, may be made subservient to the acquisition of the knowledge required. The earth being a solid of revolution, its form and magnitude may be assumed to remain the same in all ages. If this be so, the distance between the pole and the equator may be taken as an invariable quantity; and any part, say a degree, which is a nineteenth part of it, will be constant, and furnish an unalterable standard of measure. So, again, the force of gravity at the earth's surface being constant at any given place, and nearly the same at places under the same parallel of latitude, and at the same height above the level of the sea, the length of a pendulum making the same number of oscillations in a day is constant at the same place, and may be determined on any assumed scale. Thus we have two elements, the length of a degree of the meridian, and the length of a pendulum beating seconds, which nature furnishes for the basis of a system of measures. Others have been suggested, such as the height through which a heavy body falls in a second of time, determined, like the length of the pendulum, by the force of gravity, or the perpendicular height through which a barometer must be raised till the mercurial column sinks a determinate part; for instance, one-thirtieth of its own length; but these are not so capable of accurately determining the standard as the terrestrial degree, or the length of the pendulum. - By an act of Parliament passed in the year 1824, it was declared, in relation to a standard which then was in the custody of the clerk of the House of Commons, whereon were engraved the words and figures standard yard, 1760, but which was soon after burnt in the fire of the houses of Parliament, that it should be the unit or only standard measure of extension, and that it should be called the imperial standard yard. The act further declared, that if at any time thereafter the said imperial standard yard should be lost, or in any manner destroyed, defaced, # otherwise injured, it should be restored by 3 S 4

making, under the directions of the lords of the treasury, a new standard yard, bearing the proportion to a pendulum vibrating seconds of mean time in the latitude of London, in a vacuum, and at the level of the sea, as 36 inches to 39-1393 inches. It was afterwards found that this measure, when nicely examined, was incorrect, as respected the relation of 36 to 39:1393. It seems, too, never to have been directly compared with the pendulum; neither from the difficulty of determining the lengths of the seconds pendulum, except within limits too wide for the purpose in question, could the restoration of the standard be effected with any certainty. Perhaps the only standard that can be safely referred to at the present day is that belonging to the Royal Astronomical Society.

In the English system of linear measures, the unit, as we have above seen, is the yard, which is subdivided into 3 feet, and each of those feet into 12 inches. Of the yard, the multiples are, the pole or perch, the furlong, and the mile; 53 yards being 1 pole, 40 poles being 1 furlong, and 8 furlongs 1 mile. The pole and furlong, however, are now much disused, distance being usually measured in miles and yards. The English pace is 13 yards=5 feet. Thus, the following table exhibits the relations of the different denominations mentioned : —

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The measures of superficies are the square yard, foot, inch, &c., as under: —

144 square inches are equal to 9 square feet 24 square yards 10.89 square paces 40 square poles 4 square roods - - 1 square acre. In which it will be seen that the multiples of the yard are the pole, rood, and acre. Very large surfaces, as of countries, are expressed in square miles. The relations of square measure are given in the following table: –

- 1 square foot.

- 1 square yard.
1 square pace.
- 1 square pole.
1 square rood.

Square Feet. Square Yards. Square Poles. Square Roods. Square Acres. 1. 0-11 11 O-OO367.309 O-OOOO91827 O-OOOO22957 9. 1. 0-0330.579 0 000826448 0-000206612 272-25 30-25 1. 0.025 0.00625 10890. 1210. 40. 1. 0-25 43560' 4840- 160° 4." 1.

The measures of solids are cubic yards, feet, and inches, 1728 cubic inches being

to a cubic foot, and 27 cubic feet to one cubic yard. measure for all sorts of liquids, corn, and other dry goods, is declared to be the Imperial

gallon.

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By the act of 1824, the stan

According to the act in question, the imperial standard gallon contains ten

pounds avoirdupois of distilled water, weighed in air at the temperature of 62°Fahren

heit's thermometer, the barometer being at 30 inches.

The pound avoirdupois contains

7000 troy grains, and it is declared that a cubic inch of distilled water (temperature 62°,

barometer 30 inches) weighs 252.458 grains. 277.274 cubic inches.

quart, and 4 quarts one gallon.

bushel, which is 4 pecks, and the quarter, which is 8 bushels.

Hence the imperial gallon contains The gallon is subdivided into quarts and pints, 2 pints being one

Its multiples are the peck, which is 2 gallons, the

of volume are given in the subjoined table:

The relations of measures

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The old wine gallon contained 251 cubic inches, the old corn gallon 268.8 cubic inches, and the old ale gallon 282 cubic inches. Before noticing the new French, or metre, system of measures, we subjoin a few of the principal ancient ones, English inches : –

1 toise, French = 6 French feet = 6394665 English feet.

1 foot, do. = 12 French inches = 12.789.36 English inches.

1 inch, do. = 12 French lines = 1.06578 English inches.
0.0888.15 English inches.

1 line, do. = 6 French points
1 point, do. - - - - - - 0.0148025 English inches.

According to General Roy, an English fathom: a French toise :: 1000 : 106575. In the new French system, the metre, which is the unit of linear measure, is the tenmillionth part of the quadrant of the meridian = 3:2808992 English feet; and, as its multiples and subdivisions are decimally arranged and named by prefixing Greek numerals, the following table exhibits each : —

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Denomination. English Feet.
Myriametres - - 10000 metres = 328.08.'992
Kilometre - - - 1000 * 3280-8992
Hectometre - - 100 * 328 08992
Decametre - - - 10 - 32.8O8992
Metre (the unit) - - l - 3.280.8992
Decimetre - - - O-1 - O-328O8992
Centimetre - - - 0-01 - O-O328O8992
Millimetre - - - 0-001 : 0-00328O8992

The metre, therefore, is equal to 39-3707904 English inches. The unit of superficial measure, in the French system, is the are, which is a surface of 10 metres each way, or 100 square metres. The centiare is 1 metre square.

Denomination. English Square Yards.
Hectare - - 10000 square metres = 11960.33
Are (the unit) - 100 = 1 19-6033
Centiare - - l ~ 1 -1960.33

The are, therefore, is equal to 1076.4297 English square feet.
The unit of measures of capacity, in the French system, is the litre, a vessel containing

a cube of a tenth part of the metre, and equivalent to 0-22009668 British imperial gallon.

Its multiples and subdivisions are as follow:—

Denomination. Eng. Imp. Gallons. Kilolitre - - - 1000 litres =22O.O9668 Hectolitre - - - 100 = 22:0096.68 Decalitre - - - 10 = 2·20096.68 Litre (the unit) - - 1 = 0-220096.68 Decilitre - - - O-l = 0-022096.68 The unit of solid measure, or the stere, is equal to 35.31658 English cubic feet; therefore, Denomination. English Cubic Feet. Decastere - - - - 10 steres =353-1658 Stere (the unit) - - - 1 = 35-31658 Decistere - - - - 0:1 == 3•531658

Under the word Foot will be found the length of that measure in the principal places of Europe. We here think it right to add some further continuation of that article as drawn up by the late Dr. Thomas Young from Hutton, Cavallo, Howard, Vega, and others.

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The uncertainty respecting the ancient Greek and Roman measures had almost induced us to refrain from setting down the usually received notions on those subjects, but as we may be accused by the omission of neglect, we subjoin some few:—

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