when Captain Philip and nearly two hundred Indians made their appearance.

The Indians staid at a safe distance, and so did Captain Philip, though he came near enough to talk.

"Come out, old John! come out, young John! I give you good quarter," he shouted.

THE DEFENSE OF THE CABIN—Drawn by A. B. Shults.

There were only the two men, the two boys, Mrs. Kilburn and her daughter and four children, in the house, with three hundred Indians attacking them, but John Kilburn was not in the least frightened—not he. Neither was Mrs. Kilburn, nor her son or daughter. They had several extra guns; Mrs. Kilburn and her daughter knew how to load them. They would rather die than be taken prisoners. The Indians had no cannon, and their bullets would not go through the stout timbers. Only by burning the house would they be able to get in.

"Get you gone, you rascal, or I'll quarter you!" was the defiant answer that John Kilburn shouted through one of the loop-holes to Captain Philip, as the latter went back to the dark crowd of savages, who set up the war-whoop.

"They yell like so many devils," said John Kilburn; but he was not in the least disturbed by the howling.

Then the bullets began to come through the shingles on the roof, and strike against the timbers.

The Indians surrounded the house, but there were loop-holes on each side. Mr. Kilburn and Mr. Pike took two of the sides, and the two boys the others. Bang! bang! went the guns of Mr. Kilburn and Mr. Pike. Bang! bang! went the boys' guns. They could fire at a rest, and take deliberate aim. The Indians could not see the muzzles of the guns, and the moment one of the red men peeped from behind a tree his skull was in danger.

One by one they fell, which enraged them all the more, and they crept nearer, firing rapidly, riddling the shingles, hoping, quite likely, that a bullet might glance down from the roof, and hit those inside.

"The roof looks like a sieve," said John Kilburn, as he looked up and saw the holes.

Mrs. Kilburn and her daughter were loading the extra guns the while, and handing them to the men and boys, who kept up such a rapid fire that the Indians came to the conclusion that there were a large number of men in the house.

"We shall soon be out of bullets," said Mrs. Kilburn.

A thought came: why not catch the bullets that were coming through the roof? The balls had nearly spent their force when they came through, and they hung up a blanket, with thick folds, which stopped them entirely; and the girl, gathering them as they fell harmlessly upon the floor, put them into a ladle, melted them, and ran new bullets, which soon were whizzing through the air, and doing damage to the enemy.

All through the afternoon the fight goes on, the Indians aiming at the loop-holes. Their bullets pepper the logs around them. One comes in, and inflicts a ghastly wound in Mr. Pike's thigh, but the Indians do not know it, and the brave defense is kept up till the Indians, foiled in all their efforts, defeated, with several of their number dead and many wounded from the volley fired by Colonel Bellows and his men, and by those in the house, set Mr. Kilburn's wheat on fire, kill his cattle, bury their dead, and slink away, not having taken a scalp or a prisoner. They have only wounded one man.

When everything goes well with the Indian he can be very brave, but when the tide is against him he quickly loses courage and becomes disheartened, and so Captain Philip made his way back to Canada, very much crest-fallen at the repulse received at the hands of two men, a woman, two boys, and a brave-hearted girl.

[to be continued.]

CAMBRIDGE SERIES

OF

INFORMATION CARDS FOR SCHOOLS.

No. 3.

About Combustion.

BY

W. J. ROLFE, A.M.

Combustion is only another name for burning, and burning in all ordinary cases is oxidation, or union with oxygen, one of the gases that make up our atmosphere. It is a chemical change; that is, one by which we get a new substance entirely unlike any of the substances united. Common salt, for instance, is formed by the chemical union of a yellow, bad-smelling gas and a soft silvery metal. When coal and wood are burned, the chief products of the union with oxygen are carbonic acid and water. The former is a colorless gas, and the latter is in the form of invisible vapor, and both go up the chimney and mix with the outer air. The ashes left behind are only what can not be burned or united with the oxygen. If we collect all the products of the burning, together with the ashes, we find that they weigh more than the coal or wood, the increase being exactly equal to the weight of the oxygen consumed. No kind of matter can be destroyed by any power known to us; it may unite with other matter, and take many new forms, but its weight can be neither increased nor diminished. The amount of matter in the universe is always the same.

Oxygen must be heated before it will unite with coal or wood. The air is at all times in contact with them, but they will not burn unless they are first kindled. The chemical process itself, when once started, generally produces heat enough to raise more oxygen to the proper temperature, and thus the combustion is kept up. The point to which the oxygen must be heated varies much with different substances, as is well shown in kindling a coal fire. The heat produced by rubbing a match on a rough surface suffices to make the oxygen unite with the phosphorus on the end of the match; the burning of this causes heat enough for the union of the oxygen with the sulphur, and the burning of the sulphur enough to set the wood of the match on fire. The shavings, the kindling wood, and the charcoal are in turn ignited, and the burning charcoal develops heat enough to enable the oxygen to combine with the hard coal. Each step in the operation requires more heat than the preceding step. This seems a very simple thing now, but the anthracite beds of Pennsylvania long remained useless because no one had found out how to kindle the fuel, and the discovery was at last made half by accident.

There are some forms of combustion which are very unlike ordinary burning, and yet are essentially the same, being cases of union with oxygen. The only difference is that the process goes on slowly instead of rapidly. We know that vegetable and animal substances decay when exposed to the air; and decay is a slow burning. The oxygen of the air gradually combines with the substances, converting them into carbonic acid and water, and leaving only a small remnant of matter as the ashes of the lingering combustion. The heat produced in this case is found to be precisely the same as in ordinary burning, but it is set free so gradually that it escapes our notice.

We know that green wood decays much sooner than dry wood. Indeed, if wood is kept perfectly dry, it will not decay for ages. In the dry climate of Egypt wooden mummy cases have been preserved for more than three thousand years. On the other hand, dry wood burns much quicker than green wood; it is not easy to set the latter on fire. Why this difference, if decay and burning are similar processes? The decay of the green wood is due to the fact that the presence of moisture causes certain changes in portions of the wood, which enable the oxygen to attack it at a low temperature; and the slow combustion, once started, is self-sustaining. But in ordinary burning the temperature must be raised to a