LESSON XXXVII.

MISCELLANEOUS INFORMATION.

Frosts are highly beneficial to man; they assist in pulverizing the clods of earth, that is, in reducing them to powder, and bringing them into a proper state for receiving the seed.

If we take a piece of ca-out-chouc, or India rubber, and stretch it out, it will immediately return to its previous form; this quality is called elasticity.

Gutta percha is the dried juice of a large tree, grown in Asia; it is used for a variety of purposes, and it is said to be more durable than leather for shoe soles, besides being impervious to damp.

An opti"cian is a person skilled in the science of vision, and the manufacturer of telescopes, microscopes, spectacles, eye-glasses, and other instruments for assisting the sight.

A ba-rom'-e-ter is an instrument for measuring the weight of the air, and to point out the changes that are likely to take place in the weather.

Hy-dro-pho-bi-a, or the dread of water, is, perhaps, the most dreadful malady to which the human family is subject; it is caused by the bite of a mad dog.

St. Paul's cathedral was finished in the reign of Queen Anne; Sir Christopher Wren was the architect,* and although it took thirty-seven years in building, he had the satisfaction of seeing it completed.

The otter is an am-phib'-i-ous animal found on the banks of small rivers, subsisting entirely on fish, of which he destroys large numbers, eating only a part

• Ar'-ke tect

the body; he is said to be amphibious, because he lives partly on land, and partly in water; otter hunting, in former times, was a favourite diversion.

The ostrich, the largest of all birds, is a native of Africa, and also of Arabia, in Asia; this wonderful bird, when fully grown, measures about seven feet in height, and runs with such speed, that his pursuers, although mounted on their swiftest horses, have some difficulty in taking him.

The ostrich is chiefly hunted for his beautiful feathers, which are very valuable, and form a considerable article of commerce to the natives.

Red, blue, and yellow are called primitive colours, because all the other colours may be formed by different mixtures of these; thus, if I wanted a purple, I should mix a blue and red together, and these would produce a purple.

Glass is a brittle, transparent, substance, made by melting flint, or sand and soda together; it is said that this valuable art was discovered by some Pho-ni"-cian carriers of soda, who lit a fire between some lumps of this mineral, when it melted, and, mixing with the sand, produced glass.

Man differs from all other animals in his erect posture, in the beauty of his form and countenance, in his speech, and, above all, in his having a rational soul.

The plumage of our native singing birds is in general very plain and modest; having worth in themselves, they do not require a gaudy outside to recommend them to notice.

Every boy and girl has thirty-two teeth, namely, eight in-ci'-sors or cutting teeth, in front; twenty grinders, or double teeth, the farthest in the head; and four can-ine' teeth; the can-ine' teeth are the single ones, between the inci'sors and the grinders, and they

are so called because they resemble those of the dog, ca'nis being the Latin name for that animal.

Every hair of our heads, when viewed through a powerful microscope, is seen to be hollow, and is used for promoting perspiration so necessary for preserving our health.

A microscope is an instrument to assist our eyes in viewing small objects; thus, a fly seen through a powerful one, will appear a very large animal.

Evergreens preserve their leaves during the winter because their bark and leaves contain a great deal of oil, and this makes them proof against the cold of winter.

No animals can defend themselves against man; whatever speed they may have, whatever cunning they may exercise, whatever strength or weapons of defence they may possess, they cannot escape the wiles of man.

Cork is the bark of a tree somewhat resembling the oak, and growing in various parts of the south of Europe; we chiefly import it from Catalonia, in Spain.

The air we breathe is chiefly formed of two gas'es, namely, ni'-tro-gen, called life destroying air, and ox'-ygen, termed vital air; four parts of nitrogen, and one part of oxygen, are the proportions required to support animal life.

Charcoal is wood half burnt; in the process of preparing it, the wood is carefully covered with turf to exclude the air, it therefore only smothers or half-burns; charcoal is chiefly used where great heat is required, without smoke.

Plat'-i-na is the heavest of all known metals, being twenty-two times heavier than water; its colour is a light grey, and it cannot be melted without the aid of the blow-pipe; it is chiefly obtained in the Ural mountains, and is principally used for mathematical instruments, and other articles requiring great hardness.

Gold, weighing nineteen times heavier than water, is the most costly and beautiful of all the metals; it is also a perfect metal, for neither its value, nor its weight, is lessened by melting, and such is its ductility that it may be drawn out into threads much smaller than the hairs of the human head.

Gold is also so malleable that it may be beaten out into leaves so thin, that it would take three hundred thousand of them to be the thickness of an inch. The most productive gold fields at present known, are those of Australia, an English colony; and California, belonging to the United States of America.

Silver is also a perfect metal, and weighs eleven times heavier than water. Silver is found in various countries, but the greatest quantities are procured in Mexico, North America; in Peru, and at Potosi, in South America.

Besides being useful as one of our coins, Silver is extensively used for watches, tea-pots, plates, and other domestic articles, seen on the tables of the wealthy; silver is also remarkable for its ductility.

Mercury or quicksilver is fourteen times heavier than water; in this country it is always in a liquid state, but

in very cold climates it becomes a hard body, when it will spread out with the hammer.

Copper is a reddish metal, weighing nine times heavier than water; it is found in considerable quantities in the mines of Sweden; and, in our own country, the mines of Cornwall, and Anglesea in Wales, have been long noted.

Copper is a pretty metal when first melted, but it soon loses its brightness; the brazier forms it into a variety of useful articles, as, kettles, and large coppers; it may also be drawn out into wire of considerable fineness; bells are usually hung with copper wire.

Tin is a useful white metal weighing seven times heavier than water; not being liable to rust, it is extensively used for coating the different vessels used in cooking.

The common tin articles which we see exhibited in the tinman's shop, are not in reality tin, but made of iron rolled into thin sheets, and coated with tin; tin is highly malleable and when mixed with lead is beaten out into very thin leaves called tinfoil.

The tin mines of Cornwall have been wrought more than two thousand years, and they are still productive; the Prince of Wales, as Duke of Cornwall, is entitled to a duty of four shillings upon every hundred weight obtained, that the revenue derived from these mines is considerable.

Lead, eleven times heavier than water, is a soft metal of a bluish white colour, bright when newly melted; but when exposed to the air it soon becomes dull; it is procured in the mines of Yorkshire, Cumberland, Durham, Derbyshire, and some other counties.

White lead is a heavy white powder, obtained by laying thin plate lead over heated vinegar; this has the effect of corroding the lead, and reducing it to powder, and this powder when ground with linseed oil, and