m) br i under a kind of necessity to make choice of those materials which are the cheapest and most easily procured : thus, a mixture of the most improper earths and clay is often employed in the manufacture of bricks, without reflecting that two bodies specifically different in their nature, must necessarily re- quire different degrees of heat in the kiln, in order to produce an uniform hardness, and an intimate combination of parts. On the con- trary, the ancients not only select- ed the very be c »t sort of clay, but combined it with other ingredients well adapted to form the most complete cement, such as coarsely powdered charcoal and old mortar added to the clay. Of this descrip- tion, likewise, were the bricks which Professor Pallas, on his last journey through the southern provinces of Russia, discovered in the stupendous Tartar monuments, and which would scarcely yield to the force of a hammer. Another advantage peculiar to the bricks and tiles manufactured by our fore-fathers, arose from their me- thod of burning them uniformly, after being thoroughly dried. There is no doubt, that if all the defects before pointed out, were removed, and modern brick-makers wee to pay more attention to their art, by digging the clay at proper seasons, working it better than is done at present, bestowing more care on the burning of them, and particu- larly by making them much thin- ner than what is prescribed by the standard form, we might produce bricks of an equal strength and durability to those of our less en- lightened; but more provident and industrious, ancestors. Brick-layers, artisans whose business it is to build with bricks, br r and to perform brick-work ; suck as tiling, walling) chimney- work, and paving with bricks and tiles : in country places, they also under- take the masons' and plasterers' business. The London brick-layers were incorporated as a regular company in 1563, consisting of a master, two wardens, 20 assist- ants, and /8 of the livery. The art of brick-laying has been analysed in a particular treatise by Moxon; in which he describee the materials, tools, and method of working used by bricklayers. Great care should be taken that bricks be laid joint on joint in the. middle of the walls as seldom as' may be. If they be laid in winter, let them be kept as dry as possi- ble ; if in summer, they ought to be wetted, because they will then unite with the mortar better than if they were quite dry, and render the work much stronger. In large buildings, or where it is too troublesome to dip each brick separately, water may be thrown on every course after they are laid, as was judiciously done, when building the College of Physicians in London, on the suggestion of Dr. Hooke. If bricks are laid in summer, they should be covered, to prevent the mortar from drying too quickly ; because, thus it will not be cemented so firmly as if it were left to dry more gradually. In winter also they ought to be well covered, to protect them from rain, snow, and frost, which last is the worst enemy to mortar, especially if the work has become Met just before the frost happens. Oil of Bricks, a singular pre- paration, formerly much esteemed in die cure of many diseases ; but now justly exploded as absurd and pernicious rather than useful. It is
