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Mensuration of Superfices.

*

PROBLEM I.

To find the area of a parallelogram, whether 20. it be a square, a rectangle, a rhombus, or a rhomboides.

Varnishes.

(Continued from page 128.)

Best Body Copal Varnish for Coachmakers, &c.

Fuse eight pounds of fine African gum

1. Required the area of the square A B C D, copal; add two gallons of clarified oil (old whose side is 5 ft.?

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Multiply 9 by 4, and the product 36 will be the number of square feet in the required surface.

Example.-Required the area of a rectangle, whose length is 13 chains, and breadth 94 chains.

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measure); boil it very slowly for four or five hours until quite stringy; mix with three gallons and a half of turpentine; strain off, and pour it into a cistern.

21. Crystal Varnish for Maps, Prints, Charts, Drawings, Paper Ornaments, &c.

Procure a bottle of Canada balsam, draw out the cork, and set the bottle at a little distance from the fire, turning it round several times, until the heat has thinned it; then have something that will hold as much as double the quantity of balsam; carry the balsam from the fire, and, while fluid, mix it with the same quantity of good turpentine, and shake them together until they are well incorporated. In a few days the varnish will be fit for use, paror stone bottle, and kept in a gentle warmth. ticularly if it be poured into a half-gallon glass

22. Brown Hard Spirit Varnish.

Put into a bottle three pounds of gum sandarach with two pounds of shellac, and two gallons of spirits of wine, sixty over proof, and agitate it until dissolved, which will take place in about four hours time; strain, add one quart of turpentine varnish (see page 127 ante); shake and mix it well, and next day it is fit for use.

23. Cabinet Varnish.

Fuse seven pounds of very fine African gum copal, and pour in half a gallon of pale clarified oil; in three or four minutes afterwards, if it feel stringy, take it out of doors, or into another building where there is no fire, and mix it with three gallons of turpentine; afterwards strain and put aside for use.

24. Milk of Wax.

Melt, in a porcelain capsule, a certain quantity of white wax, and add to it, while in fusion, an equal quantity of spirit of wine of sp. gr. 0.830; stir the mixture, and pour it upon a large porphyry slab. The granular mass is to be converted into a paste by the muller, with the addition, from time to time, of a little alcohol; and as soon as it appears to be smooth and homogeneous, water is to be introduced in small quantities successively, to the amount of four times the weight of the This emulsion is then to be passed through canvas, in order to separate such par13 acres 0 rds. 10 perches. ticles as may be imperfectly incorporated.

123

61-1

10) 130 chains.

(To be continued.)

* Area is the superficial measure contained within the surface of any plane figure; and the surfaces are measured by squares; as square inches, square feet, square yards, &c. A square whose side is one inch, one foot, &c., is called the measuring unit.

wax.

(To be continued.)

*We beg to state, in answer to several correspondents, that, when we have collected together all the receipts for varnishes that we possibly can, we will append some general remarks upon the method of preparing them, and also upon their employment.-ED. DECORATOR'S ASSISTANT.

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Pottery.

sponge when necessary. Only round vessels can be made on the wheel; those of other shapes are made in moulds of plaster. Handles and other solid parts are pressed in moulds, and stuck on while they and the vessels are still wet. The vessels thus formed are first dried in a stove, and, when dry, burned in a kiln. They are in this state called biscuit. If they are finished white, they are glazed by another process. If they are figured, the patterns are engraved on copper, and printed on coarse paper rubbed with soft soap. The ink is made of some colour that will stand the fire, ground with earthy matter. These patterns are moistened and applied to the porous biscuit, which absorbs the colour, and the paper is washed off, leaving the pattern on the biscuit.

THERE are two kinds of pottery-common potters' ware, and porcelain of China. The first is a pure kind of brick; and the second a mixture of very fine brick and glass. Almost all nations have some knowledge of pottery; and those of the very hot countries are sometimes satisfied with dishes formed by their fingers without any tool, and dried by the heat of the sun. In England pottery of every sort, and in all countries good pottery, must be baked or burned in a kiln of some kind or other. Vessels for holding meat and drink are almost as indispensable as the meat and drink themselves; and the two qualities in them that are most valuable, are, that they shall be cheap, and easily cleaned. Pottery, as it is The employment of machinery to do all the now produced in England, possesses both of heavy part of the work, the division of labour, these qualities in the very highest degree. A by which each workman acquires wonderful white basin, having all the useful properties of dexterity in his department, and the conductthe most costly vessels, may be purchased for ing of the whole upon a large scale, give bread twopence at the door of any cottage in Eng-to a vast number of people, make the pottery land. There are very few substances used in cheap, and enable it to be sold at a profit in human food that have any effect upon these almost every market in the world. It is not vessels; and it is only rinsing them in hot seventy years since the first pottery of a good water, and wiping them with a cloth, and they quality was extensively made in England; and are clean. before that time what was used was imported, the common ware from Delph, in Holland (from which it acquired its name), and the porcelain from China. We now annually export fiftythree million pieces of earthenware to all parts of the world.-Charles Knight.

The making of an earthern bowl would be to a man who made a first attempt no easy matter. Let us see how it is done so that it can be carried two or three hundred miles and sold for twopence, leaving a profit to the maker, and the wholesale and retail dealer. The common pottery is made of pure clay and pure flint. The flint is found only in the chalk-A French surgeon states, that by fitting bedCONSTRUCTION AND POSITION OF BEDSTEADS. counties, and the fine clays in Devonshire and steads with glass feet, and insolating them about Dorsetshire; so that the materials out of eighteen inches from the wall of the apartment, which the pottery is made have to be carried he has cured the patients sleeping on them of from the south of England to Staffordshire, many nervous affections. Suspicions are beginwhere the potteries are situated. The great ning to arise too, that our well-being may be advantage that Staffordshire possesses is abun-affected by sleeping parallel to, or at right dance of coal to burn the ware and supply the angles with, the line of the terrestrial magnetic engines that grind the materials. The clay is worked in water by various machinery till it current. The house in which we live has a considerable influence on our sensations somecontains no single piece large enough to be times little suspected. visible to the eye. It is like cream in consistence. The flints are burned. They are IMPROVEMENT IN LIGHTHOUSES.-A gentlefirst ground in a mill and then worked in water man in Oxford, N.Y., has a mode of furnishing in the same manner as the clay, the large lighthouses with the Drummond light, to be pieces being returned a second time to the supported by gases produced by magnetomill. When both are fine enough, one part of electrical machines, which are to be kept in flint is mixed with five or six of clay; the operation by the power of water descending whole is worked to a paste, after which it is from an elevated reservoir, which reservoir is kneaded either by the hands or a machine; and to be occasionally replenished by pumps when the kneading is completed, it is ready for operated by a windmill mounted above the the potter.

lantern.

He has a little wheel which lies horizontally. EXTENSION OF THE ELECTRIC TELEGRAPH.He lays a portion of clay on the centre of the The posts for the electric telegraph have been wheel, puts one hand, or finger if the vessel is put down, and the wires laid, along a part of to be a small one, in the middle, and his other the Liverpool and Manchester Railway;-so hand on the outside, and, as the wheel turns that in a month or two we may hope to have a rapidly round, draws up a hollow vessel in an telegraphic communication from Liverpool to instant. With his hands, or with very simple London vid Manchester. This is rather a tools, he brings it to the shape he wishes, cuts roundabout way for the first outport, in the it from the wheel with a wire, and a boy car-empire to communicate with the capital: but ries it off. The potter makes vessel after ves-as the speed of the electric communication sel, as fast as they can be carried away. They surpasses that of everything except thought, are partially dried; after which they are thirty miles more or less is quite unappreciable. turned on a lathe and smoothed with a wet-Manchester Paper,

Steam-Boiler Explosions.

To the Editor of the DECORATOR'S ASSISTANT. SIR, A late disastrous accident, both to life and limb, has suddenly aroused public attention to a subject of the most vital importance. It is a well-known fact, both with regard to steam engines on land and water, that they are attended by a parcel of ignoramuses, many of whom might have some difficulty in distinguishing the safety-valve from the furnacedoor in an emergency; and when I speak thus it is from an experience which I should have no desire to again undergo, namely, that of being blown through a roof twice. Surely this state of things should not be allowed to continue without legislative interference.

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Required-The method of making "sensitive pictures."— W. S. B.

Required-A recipe for preparing gold and silver inks.

S. JONES.

lopes is performed, and especially the black-bordered ones.-D. N. O.

Required-Information as to the method by which the stopper of a glass decanter can be withdrawn, having tried several without success.-D. T. (Chelsea).

A SUBSCRIBER FROM THE COMMENCEMENT (Exeter).-We will do so shortly; at present we are preparing the materials for them. D. N. O.-Shortly.

T. B. A.-The representation of a bridge given in our "Glossary" was an engraving of that of Taff, in Glamorganshire. It is formed of one arch, having a span of mere than 140 feet. It was designed by a poor, uneducated man; but his industry, courage, and perseverance in effecting his object is well worthy of record. His first attempt failed, in consequence of the enormous pressure of the haunches or sides of the bridge, which forced up the keystone, and, in order to obviate this, he pierced the stonework with cylindrical apertures, which remedied the defect. Prior to the erection of this bridge, that of the Rialto had the largest span of any in existence. MATHEW C. (Liverpool).-According to Smeaton, a horse will raise 22,9161b. one foot high in a minute; but the following make the amount larger, thus:

A.

The

Desaguliers Watt... ... Grier ...

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L.-The Paris royal foot of twelve inches (old system) correspondent who has been kind enough to give us a equals 12.7977 English inches. week's labour in the shape of about two dozen queries, the answer to one of which alone would entirely fill the DECORATOR'S ASSISTANT, is respectfully informed that we have no desire just at present to metamorphose ourselves into a calculating machine.

HENRY SMITH (Southwark).-A beautiful green paint may be made by adding to a hot solution of sulphate of copper (blue vitriol) a little solution of carbonate of soda; a beautiful powder, generally known by the name of "French green, " will be precipitated. The powder is sub-carbonate of copper. AQUA (Nottingham).-Copper-plate ink is prepared by mixing the best Frankfort black with about sixteen times its quantity of drying hut or linseed oil.

E. N. C. (Edinburgh) inquires for "a method of improving glue, so as to make it melt quickly, hold the heat for a length of time, and when used on wood dry well without taint." We, ourselves, only know of one method, and that is to add a gill of vinegar, alcohol, or cyder, when dissolving the glue, in a common pot, and afterwards adding as much water as is found necessary. If any of our readers are acquainted with any other plan, they will oblige us by communicating it.

AN ARTISAN AND ADMIRER OF THE "DECORATOR's ASSISTANT" (Hull).-The article on "Varnishes" will be rendered as perfect as possible, and will be followed by one on "Cements."

G. H. (Paddington).—" Scagliola" is prepared by making a
pap of finely-ground calcined gypsum, mixed with a weak
solution of Flanders glue. The surface is turned smooth
upon a lathe, polished with stones of different degrees of
fineness, and finished with some plaster pap to give it
lustre. Pillars and other flat surfaces are smoothened by
a carpenter's plane, with the chisel finely serrated, and
afterwards polished with plaster by friction.-In answer to
your second question, see reply to "J. S.," in No. 15,
page 120.
Mr. Campbell, of Birmingham, is thanked for the enclosure.
We will make use of the designs.

ANSWERS TOO TRIVIAL OR INAPPROPRIATE.-Velocipede,
Henry D., C. T. H., N. G., A Carver.
CONTRIBUTIONS RECEIVED.-Franklin, O. R., MS.
CONTRIBUTION THANKFULLY DECLINED." Hindu Archi-

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London : Published at the Office of the SPORTING LIFE, 17, Holywell-street, Strand (where all commuof all Booksellers.-Saturday, September 11, 1847. Printed by W. COOLE, Lumley Court, Strand.

Required-The process of writing and gilding on glass.-nications to the Editor are to be addressed); and to be had

W. M.

Required-The manner in which the manufacture of enve

An Illustrated Glossary of Technical Terms used in Architectural and Interior Decoration.

(Continued from page 130.) CAR, a description of carriage or warchariot, drawn by beasts of burden. The cars of the different divinities are drawn by those animals which are sacred to each; as that

of Mercury by rams, of Minerva by owls, that of Venus by swans or doves, that of Apollo by griffins, of Juno by peacocks, and that of Diana by stags.

CARYATIDES (in architecture), figures of women clothed in long drapery, mermaids,

shut. Also an old English name for the deep hollow moulding similar to the scotia. It is

much used in the perpendicular style, and is frequently enriched with scrolls, &c.

CAST, anything formed by means of a mould.

CASTING OF DRAPERIES (in sculpture and painting), the proper distribution of the folds of garments.

CASTING-UP, a technical term used among artisans, signifying reckoning or calculating.

CASTLE (in architecture), a fortified building. CAVEDIUM (in ancient architecture), an open court within the body of a house.

CAVETTO, a concave mould of one quarter of

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a circle, used in the Grecian and other styles of architecture.

CAULICOLI (in architecture), little stems or stalks resembling twists or small volutes un

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derneath the flower, or the abacus in the Corinthian column.

CEILING, the inside of a roof in buildings, or the top of a room, in which latter case it is generally formed of laths and plaster.

CELLAR (in architecture), an apartment in the foundation of a building generally used for holding stores, &c.

CEMENT, any adhesive substance employed for uniting materials.

CEMETERY, CEMETERY, or CIMETERY, a burial place.

CENOTAPH, or CENOTAPH, & monument erected to the honour of a deceased person. CENTAUR, a figure of which the head and

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