held to be in these early times quite an event in the history of the State Department, where the clerical part of the work was then performed.

During the years from 1790 to 1812 inventors confined themselves almost wholly to agricultural and commercial objects. Implements for tilling the soil and converting its products and machinery for navigation attracted most attention. Manufactures, except of a purely domestic character for domestic purposes, were hardly known; the arts were poorly understood and little cultivated. The necessities of the New World drove its enterprise into other channels, and its people looked to Europe for manufactured products not directly connected with the necessities of life or demanded by the development of its commerce and agricul ture. The war of 1812, however, forced our people to attempt production in many branches of manufacture and industry heretofore almost wholly uncultivated, and the result was the most remarkable development of human ingenuity ever known to any age or country. It is a source of great regret that no well-preserved history of American inventions dating from this time is in existence, and that no classified list of models which were in the Patent Office at the time of the fire in 1836 can be obtained. The earliest date that can be reached is January 21, 1823, and that is only partially complete.

Improvements in modes or machines for manufacturing common bricks received but little attention until about 1840; previously they were more remarkable for uniqueness in some special point of but small importance, than for any

ner.

generally good achievements; that is, no attention was paid to the result of the brick after it came from the kiln; the whole idea seemed to be to shape or mould it in some manFor instance, one machine was made like a box now used by plasterers to run off their lime; it was elevated slightly, and the mud, which was mixed in the box, allowed to pass through a grate into a large framework having sides about three inches high, and divided by wires stretched the length and across it, which laid upon the bottom, and when the clay in the shallow box was somewhat hardened the wires were raised and the bricks thereby cut and formed into shape. The box, when emptied of the clay, could be easily moved on wheels running on a plank gangway, to the next shallow mould-box, and so on. But the slush stock made in this way was very inferior; it would dry unequally, be full of cracks, and was subjected to no packing, as in the pug-mill, or pressure, as by machines of to-day, or a blow, as is done by the hand-moulder, who dashes the tempered and packed clay into the mould with great force, and again forces it down and closer together with his hands. and plane. When the bricks came from the kiln they were light, very open or porous, therefore absorbed water readily, and were entirely unfit for building purposes.

The brick machines which will be hereafter described have remedied these great objections in almost every particular. With every machine and contrivance which is to be described in this volume I am perfectly familiar, and have seen all in actual operation, and for this reason have selected such for illustrating the different portions of

this work. There are other contrivances and machines made in this country and in Europe that may be equally as good as some herein described, and no effort will be made to praise those which shall be used for illustrations above others which may have equal claims for consideration. The thousands of inventions cannot all be described, and rather than fall into a sea of error, so common in mechanical descriptions, I shall be compelled to select those machines the merits or demerits of which I can personally discuss.

Before any attempt is made to describe the processes or machines employed in the manufacture of bricks or the other branches of pottery, it is highly important that there should be a thorough knowledge of the character of clay, and some of its changes while under the several conditions to which it is to be subjected. This will be attempted in a general way for bricks, in the chapter which is to immediately follow, and more especially for the other subjects in the portions of the book devoted to them; for instance, fireclays will be more fully described in Chapter VI.; terracotta clays in Chapter VII.

CHAPTER II.

THE DIFFERENT VARIETIES OF CLAY, THEIR CHARACTERISTICS, QUALITIES, AND LOCALITIES.

THE term clay is applied to hydrus silicates of aluminum, and is found, combined with other substances, in beds of varying depths, being produced for the most part by the decomposition of felspar rocks, and the precipitation in basins, from the suspension in water, of the finely divided impalpable particles. The rocks containing a good proportion of oxide or salts of iron form red clays, and those having only traces form white or light clays.

Pure clay or the hydrus silicate of alumina is infusible, even in the most intense heat; but when mixed with the alkalies or alkaline earths, it becomes fusible in proportion to the admixture.

Clay suitable for the manufacture of building bricks is an abundant substance, and is commonly obtained from sedimentary or alluvial deposits; but there is a great difference in the nature and quality of clays found in various localities; in Maine, the clays are light; in Massachusetts and Rhode Island they are more fatty; the Haverstraw, Croton, and other clays on the Hudson River contain an undesirable quicksand," and the bricks made from them usually "whitewash" or "saltpetre" upon exposure to the weather.

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The Connecticut and northern New Jersey building brick clays resemble those of the Hudson River; but the belt extending along the eastern portion of Pennsylvania, down through Delaware, Maryland, the District of Columbia, and the northeastern portion of Virginia contains the finest grade of loamy clay, producing a superior quality of bricks of the greatest hardness, and of a cherry-red color.

Baltimore and Philadelphia lead in regard to the quality and color of the finer grades, but the ornamental bricks produced in Philadelphia are of the highest rank. The clay formerly used in Chicago and vicinity was not only limy, but contained lime pebbles, which rendered it very difficult to work; but recently it is claimed that good banks of clay have been discovered near the city, which promise to produce superior bricks. Around St. Louis the material is of a loamy nature, with veins of what are called "joint clay," which makes the bricks crack and check in drying, and split in burning. The clays in the neighborhood of Milwaukee are of a plastic nature, and owing to only a small per cent. of iron, burn nearly white, or of a light cream color.

The clays in many portions of Canada are good for brickmaking; they are especially so in the neighborhood of Amprior, Belleville, Bell's Corners, Brantford, Dundas, Glenwilliams, Kincardine, London, Pembroke, Ramsay, and Yorkville, in Ontario; and near Little River, Montreal, Quebec, and St. John, in Quebec, also at St. John, and many portions of New Brunswick. The clays found near Halifax, Springville, and Woodstock, in Nova Scotia, are passably fair for brick-making.