with neither top nor bottom. One plunger from above and another from below strike the clay in the mould with much force, and make the fine, smooth brick known as "pressed brick." All this is done by machinery, and some machines make six bricks at a time. These "dry" bricks are fragile before they are burned, and must be handled with great care.

Bricks cannot be put into the kiln while they are still wet, for when a brick is drying, it is a delicate article. It objects to being too hot or too cold, and it will not stand showers or drafts. In some way about a pound of water must be dried out of each brick; but if you try to hurry the drying, the brick turns sulky, refuses to have anything more to do with you, and proceeds to crack. To dry, bricks are sometimes spread on floors; or piled up in racks on short pieces of board called "pallets"; and sometimes they are put upon little cars and run slowly through heated tunnels. The last is the best way for people who are in a hurry, for it takes only from twenty-four to thirty-six hours to make the bricks ready to go to the kiln to be burned.

In one sort of kiln, the bricks themselves make the kiln. They are piled up in arches, but left a little way apart so the hot air can move freely among them. The sides of the structure are covered with burnt brick and mud, but the top is left open to allow the steam from the hot bricks to escape. The fires are in flues that are left at the bottom. They must burn slowly at first, but after a while, some forty to sixty hours, the heat becomes intense. Thus far the bricks have been grayish or cream-colored, but now, if there is iron in them, they turn red; if there is lime, they turn yellow; if a large amount of lime, they become flesh-colored. Besides this sort of kiln, which is torn down when the bricks are sufficiently burned, there is also the permanent kiln, which has fixed side walls and either an open or closed top. Then, too, there is a "continuous" kiln. This has a number of chambers, and the heat from each one passes into the next; so that bricks in one chamber may be just warming up while in another they are ready to be taken out.

When the bricks come out of the kiln, some of them are good and some are not. Those that were on the outside are not burned enough; those next it are not well baked, but can be used for the middle of thick walls. The next ones are of good quality; but those directly over the fires are so hard and brittle that they are of little use except for pavements.

Paving-bricks, however, are not to be despised. They are not as smooth and well finished as pressed brick, but they are exceedingly useful. They need as much care in making as any others, and they must be burned in a much hotter fire to make them dense and hard. The tests for paving-bricks are quite different from those for ordinary building-brick. If first-class paving-bricks weighing fifty pounds are soaked in water for twenty hours, they take up so little water that they will not weigh more than fifty-one or fifty-one and a half pounds when taken out. To find out how hard they are, the bricks are weighed and shaken about with foundry shot for a number of hours. Then they are weighed again to see how much of their material has been rubbed off. A third test is to put one brick on edge into a crushing machine to see how much pressure it will stand. Paving-brick is cheaper than granite blocks, and if it has a good foundation of concrete covered with sand, it will last about three fourths as long. Brick is less noisy than stone and is easier to clean.

Not so very long ago, when particularly handsome bricks were needed for the outside of walls and other places where they would be conspicuous, they were "re-pressed"; that is, they were made by hand or in a "soft-mud" machine, and then, after drying for a while, were put into a re-pressing machine to give them a smooth finish. These machines are still used, but they are hardly necessary, for the "dry-clay" brick machine will turn out a smooth brick in one operation.

Another substance which is made of almost the same materials as brick is terra cotta. To make this, fire brick, bits of pottery, partly burned clay, and fine white sand are ground to a powder and mixed very thoroughly. This mixture is moulded, dried, and burned. Until recently, all terra cotta was of the color that is called by that name, but now it is made in gray, white, and bronze as well.

Bricks are laid in mortar, and this makes a wall one solid mass and stronger than it could be without any cement. But mortar does more than this. It is more elastic than brick, and therefore, when a wall settles, the mortar yields a little, and this often prevents the bricks from cracking. Bricks are always thirsty, and if one is laid in mortar, it will suck the moisture out of it almost as a sponge will suck up water. The mortar thus has no chance to set, and so is not strong as it should be. That is why the bricklayer wets his bricks, especially in summer, before he puts them in place. Lime or cement mortar will not set in freezing weather, and a brick building put up in the winter is in danger of tumbling down when the warm days of spring arrive.

This thirstiness of bricks is their greatest fault. Three or four days of driving rain will sometimes wet through a brick wall two feet thick, crumbling the plaster and spoiling the wallpaper. That is why it is a poor plan to plaster directly on the brick wall of a house. "Furring" strips, as they are called, or narrow strips of wood, should be fastened on first and the laths nailed to these, or the wall can be painted or oiled on the outside. The best way, however, though more expensive, is to build the wall double. Then there is air between the two thicknesses of brick. Air is a poor conductor of heat; so in summer it keeps the heat out, and in winter it keeps it in.

But brick will suck up water from the ground as well as from a storm; and therefore, when a brick house is to be built in a wet place, there ought to be a three-eighths-inch layer of something waterproof, like asphalt and coal tar, put on top of one of the layers of brickwork to prevent the moisture from creeping up.

Bricks have their faults, but they will not burn, and when properly used, they make a most comfortable and enduring house.

V

AT THE GOLD DIGGINGS

When gold was first discovered in California, in 1848, people from all over the world made a frantic rush to get there, every one of them hoping that he would be lucky enough to make his fortune, and fearing lest the precious metal should be gone before he could even begin to dig. The gold that these men gathered came from what were called "placers"; that is, masses of gravel and sand along the beds of mountain streams. Each miner had a pan of tin or iron, which he filled half-full of the gravel, or "pay dirt," as the miners called it. Then, holding it under water, he shook off the stones and mud over the side of the pan, leaving grains of gold mixed with black sand at the bottom. This black sand was iron, and after a while the miners removed it with a magnet, dried what remained, and blew away the dust, leaving only the grains of gold.

Another contrivance which soon came into use was the "cradle." This was a long box, sometimes only a hollowed-out log. At the top was a sieve which sifted out the stones. Nailed to the bottom of the cradle were small cleats of wood, or "riffles," which kept the water from running so fast as to sweep the gold out of the cradle with it. The cradle was placed on rockers and was also tilted slightly. The miner shoveled the gravel into the top of the