When was cotton paper invented?

In the twelfth century, but it was not much used till the discovery of printing made a demand for it. Who were the first printers of whom we know?

The Chinese.

When was the first book printed in Europe?

In A.D. 1450 or 1452.

What was it?

The Bible.

Who was the first English printer?

William Caxton. The first English book was printed by him in the Almonry at Westminster Abbey.

How were books made before printing was found out?

They were written by hand. Could people ever be educated in great numbers if this were the way of making books now?

No, for both in price and in their fewness, written books would be beyond the reach of most people.

LIBRARIES.-Kiriath-Sepher, Book City, in Canaan (Jud. i. 11). Ancient Thebes. Pergamos, Asia Minor (hence parchment), 200,000 vols., B.C. 133. Alexandria, twice destroyed; by fire (B.C. 48), 400,000 vols.; by Caliph Omar (A.D. 634), 700,000 vols. Bodleian, Oxford, 100,000 vols. Royal Library, Paris, 800,000 vols. in 1860. British Museum Library, London, over 600,000 vols.

may I often have to say it, for your sake and my own. We have had a famous time of it since the Holidays began. George and Mary came home, and the three of us have been to a great many places, for Uncle is here from the country, and as he has nothing else to do but enjoy himself, he has taken us with him to more sights and amusements than we ever had at Christmas time before.

It has been cold here, but not cold enough

sa as to let

to freeze the water in the Barks, us have skating. My cock canary is dead. They forgot to cover it up with a cloth one cold night, and it was ill in the morning and died in a day or two.

In another fortnight we shall be at School again, and I shall try to work harder than

I have done, for they are very much grieved

here to find

me so low in my class.

I remain, dear Henry,

Your sincere friend,

Boobert Warrington.

To Mr. Henry Simpson,

16, Birmingham Street,
Edinburgh.

LESSONS ON SPECIFIC SUBJECTS.

PHYSICS.-MATTER AND MOTION.

1. THE DIFFERENT STATES OF MATTER.

1. Matter-that is, the material of which all things consistpresents itself to us in one of three different conditions: either solid, as in a stone; liquid, as in water; or gaseous, as in the air we breathe.

2. Bodies are not, however, limited to any one form. For example, oxygen-which forms part of the air, as one of its gases -forms part of water as well, and part also of many solid bodies; so that we find it in all the three conditions-solid, liquid, and gaseous.

3. A solid is a body made up of particles more difficult to separate from each other than the particles of a liquid. A liquid, again, is a body whose particles are less easily separated from each other than those of a gas. You see this constantly in daily life; for while you can pass your hand through the air without feeling almost any resistance, you cannot pass it without some effort through water, and it is impossible to pass it through a solid body. All bodies are composed of extremely minute atoms, which, in a solid, hold together so that they require strong force to divide them; whereas, in a liquid, they separate from each other, and combine into new relations from very slight disturbances, as when you part water with your finger. In gases, again, the separation of the particles is still more easy; as, for example, when we move a wand through the air without our feeling almost any hindrance. We need to saw asunder a solid body, or split it; but a child's toyboat parts the surface of a pool, and a butterfly cleaves the air at its will.

2. THE GENERAL PROPERTIES OF MATTER.

1. Divisibility.-All substances are capable of indefinite division. The finest dust into which a stone may be ground proves, when seen under a microscope, to be a block, which might be still further divided to any extent, if we had the means of doing so. A grain of salt dissolved in a glassful of water is so divided that the minutest

drop contains a particle of it. The thinnest part of a soap bubble was shown by Sir Isaac Newton to be not more than the 2,500,000th part of an inch in thickness, at the moment before it bursts. A hundred threads spun by a spider do not make up the twenty-fifth of an inch in thickness, and gold may be so drawn out that a coating of it, weighing only the 432,000,000,000th part of an ounce, appears, under the microscope, a continuous plate of solid gold, on the surface of a portion of silver wire which it has been used to gild. The odours of bodies are caused by minute particles of them which fly off into the air and come in contact with our organs of smell, but so inconceivably small are these atoms, though they affect us so powerfully, that the substances which yield them, are in many cases, not perceptibly lighter after long periods of exposure. A piece of musk, for instance, after scenting a chamber for months, is found to weigh so little less that our finest scales cannot detect any loss it has sustained. And how small must the coloured particles of a glass of wine be when a glassful will tinge the whole of a great jar of water? How small must the particles of water be which rise in vapour from the earth continually without our seeing them, or without the finest microscope being able to detect them? A single drop of stagnant water has been calculated to contain not fewer than 500,000,000 of living creatures. How inconceivably minute must the vessels of their bodies be, and what shall we think of the particles of food which circulate through such tubes and ducts?

2. Compressibility.-All bodies may be pressed into smaller bulk, to a greater or less degree, in proportion to the spaces between the atoms of which they are composed, the density, or thickness, of any body, and its resistance to further pressure, of course increasing in proportion as it may have been compressed. Metals, when pressed by the die into medals or coins, are sensibly smaller than they were before. As to sponge, cork, and the like, we all know how they may be squeezed into very small bulk. Air and other gases are the most compressible substances in nature. You may readily see this in the case of air by pressing a tumbler, mouth downwards, into a vessel of water. The water will rise in the tumbler in proportion to the depth to which you immerse it, the air having been forced into smaller bulk by the greater or less weight of water pressing against it. An empty bottle, corked as tightly as possible, will have the air so compressed that the cork will be forced in, if the bottle be sunk deep into the Water and other liquids are, on the other hand, the most

sea.