taken but little warmer than the temperature of the atmosphere; and thus, by the gradual manner in which they have parted with their heat, time has been allowed for the regular contraction of the whole into a uniform and consistent substance.

THE MANUFACTURE OF CROWN GLASS.

The name of Crown Glass is given to the best kind of window glass The ingredients of which it is made are, with some variations in different factories, as follows:-120 parts, by weight, of white sand; 60 purified pearlash; 30 saltpetre; 2 borax ; 1 arsenic. It differs from flint glass in its composition, by containing no lead; it is much harder and harsher to touch than flint glass; but when well made, is a very beautiful article.

The manufacture of the common window glass, though made by blowing, is conducted differently from that of flint glass, as it is the object to produce a large, flat, and very thin plate of glass, which is afterwards cut by the glazier's diamond into various shapes. The furnaces employed are different in construction to those used in the making of flint glass, but the principle of the working is much the same. Few tools are used in the blowing and flashing. When the materials are properly mixed and refined, the workmen commences his operations precisely in the same manner as in the blowing of the other glass. He gathers from the crucible as much glass upon his iron tube as is necessary for the formation of a sheet of glass of the usual size, which generally weighs from ten to eleven pounds. The lump of glass sticking on the end of the tube is first rolled on an iron table, and afterwards

blown into a pear-shaped form. It is then heated again. A second blowing makes it swell to a greater size. A third time it is heated and blown, the globe still getting larger in bulk and thinner in substance. The side opposite the tube is now flattened by pressure against a smooth surface, and it is then ready to be taken from the tube used in blowing. An assistant now takes a solid iron rod, smaller and lighter than the tube used for blowing. He collects a small piece of melted glass on the end of this rod, and applies it to the centre of the flashed side of the glass bubble; there it sticks fast, so that the bubble is held between the tube on one side, and the rod on the other.

A small piece of iron, wetted with cold water, is then drawn round that part of the glass which is connected with the tube, and the glass cracks in the circle traced by the cold iron. The workman gives a smart blow to his tube, the circular crack separates at once, and the glass is left attached to the solid iron rod on the flattened side, and having a round hole opposite to it on the other. The glass is now heated again, in order that the flattened globe may be converted into a plane surface like that of a round tube. This process is called flashing," and a very extraordinary process it is.

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The workman, who is called the flasher, screening himself on one side of the furnace, by the wall, rests the iron rod on a hook placed over the mouth-hole, and begins to whirl it slowly at first, then faster and faster, till it flies open into one plane disc of glass, from 50 to 60 inches in diameter. He then walks off with the circle of glass, keeping up a slight rotation as he moves along, and when it is sufficiently cool, he turns down his rod and lays the glass on a block of fine clay.

The rod upon which the glass was whirled, is disengaged in the same manner as the blowing-pipe was before, by touching the surrounding glass with a cold wet iron. The finished plate is put, resting on its edge, to cool gradually in an annealing oven. Large plates of crown glass, such as are required for glazing engraved prints, used formerly to be imported from Germany. This country has, however, for a long time been not only independent in this respect, of all foreign manufactures, but similar plates of English make are exported to a considerable

extent.

Broad glass is a common, coarse description of window glass; and, since the removal of the duty in this country, it has become exceedingly cheap, although the public pay a vast deal more for it than they ought to pay. The process of its manufacture is somewhat different to those already described, and is as follows:

:

The proper quantity of glass being collected upon an iron tube, it is then expanded by the workman's breath into an elliptical shape of about twelve inches in diameter, and of the proper thickness. This done, the glass is carried to the mouth of the oven, and the end of the tube through which the workman has blown being closed, the further expansion by heat of the confined air within the globe causes it to burst in its weakest part. While still hot and ductile, it is opened by a pair of shears into its centre length, into a flat plate, which is then conveyed to the annealing oven.

BOTTLE GLASS.

The composition of bottle or green glass is various in different parts of the kingdom. It is usually made with sand,

lime, and sometimes clay, alkaline ashes, and sometimes the vitreous slag produced from the fusion of iron ore, and also soap makers' waste. The principal manufacture of this article is at Newcastle-upon-Tyne. Articles made of bottle-glass are fashioned by the same process as those of flint glass, with the exception of wine and beer bottles, the containing parts of which are blown in metallic moulds. The green colour of this kind of glass is owing to the presence of a portion of iron in the sea sand, and the vegetable ashes of which it is composed.

Something about a Slabe who returned Good for Ebil.

LAVERY, my young friends, is a cruel and wicked thing. There are, thank God, no slaves in England. The moment a slave touches the ground of Old England he is Free! and no tyrant master, however strong he may be in physical force or wealth, can touch him. This is, indeed, a

great blessing, and we cannot be too thankful to our ancestors, who made England a free country; but, above all, we should be grateful to Almighty God, for the great measure of liberty he has given to us, and for having raised up, for the cause of the poor slaves in other countries, such good men as Wilberforce, Buxton, and Clarkson, whose noble efforts for the emancipation of our black brethren, are among the noblest deeds of noble men in any age or nation, and Peter Parley would have all little children unite with such men in their endeavours to put an end to slavery wherever it is found.