Obs. The loadstone, which possesses the singular and unaccountable property of always pointing to the north, is an ore of iron.

88. Tin is an English or Cornish metal, 7 times heavier than water. It is very malleable; and is highly useful as a coating to iron and copper; requiring only, to have iron dipt into it, and copper to be rubbed with it, to become perfectly coated.

89. Lead is 11 times heavier than water; easily melted, and highly useful for various purposes.

90. Nickel is a Chinese metal of a light grey; 9 times heavier than water, and melted with difficulty.

91. Zinc is 7 times heavier than water, of a bluish white colour, and used in various compounds.

92. The other metallic substances are Antimony, Bismuth, Cobalt, Arsenic, Manganese, Palladium, Rhodium, Potassum, &c., to the number of thirty; although the ancients knew of only seven metals.

93. Iron is formed into steel, by being heated with charcoal. Brass is a compound of zinc and copper. Bell-metal is brass with a little silver. Pewter is a mixture of tin, lead, and brass. Bronze is a mixture of copper and tin.

94. Coals are minerals dug out of the ground in immense mines; and they are the best fuel yet discovered by man. The British islands are celebrated for their coal-mines; many countries being obliged to depend on wood; which is often scarce and dear.

95. Half the civilized employments of man, consist in working the metals and minerals. In England, the large towns of Birmingham and Sheffield are wholly engaged in the useful and ornamental manufactures of various metals.

96. Civilization depends so much on the discovery of the useful metals, that little progress can be made from a savage state, without the useful trade of a blacksmith.

He makes all the implements of gardening and agriculture; all domestic utensils; knives to cut with; and spears and swords to defend the soil and its produce, against invaders.

97. To avoid the inconvenience of exchanging or bartering, men, in early ages, fixed on metals; as on gold, silver, copper, or iron, for a medium of value: so that, if one man had too much corn and wanted wine, he was not obliged to give corn for the wine, but he might sell his corn for so much metal, and buy the wine with the metal, at his convenience.

Obs.-Hence, the origin of money; and as it was found inconvenient to weigh metal in every transaction, (as Abraham did when he bought the burying-place of Sarah;) stamps were put on pieces of metal, to indicate that they might be safely received for a settled weight or value. Hence, there are pieces of stamped gold of known value; as guineas, half guineas, eagles, half eagles, &c. pieces of stamped silver, as crowns, dollars, half dollars, &c.: and pieces of stamped copper; as cents and half cents:-all of universal worth.

V. Of Building.

98. Man, like other animals, would seek places in which he might shelter himself, from the incle mency of the weather. Beasts of prey retire to thickets and caves; beavers build mud houses; and rabbits make burrows under ground. Man, in his most savage state, imitates their practices; and then improves on them, by the aid of his

reason.

99. Among the savage tribes in Siberia and the most northern parts of America, their habitations are constructed in the rudest manner, principally with earth intermixed with leaves, twigs, and the stems of weeds, &c. and the bottoms of their huts are frequently partly under the ground or the snow, and are thus more effectually closed during the long continuance of their winter season. In warmer regions, the American Indians build wigwams of stakes, leaves, turf, and straw in the shape of a soldier's tent.

In Africa, the materials of the kraals are the same as the wigwams; but the shape is circular, with a hole at the top to let out the smoke; and the entrance is so low, in order to keep out beasts of prey, that the inhabitants crawl in and out.

100. A number of these habitations in one place; or a collection of wigwams or kraals, forms a Siberian, American, or African tribe. In many islands of the South Seas, the natives, when first discovered, had learnt to elevate the roofs on poles, and to fill in the sides of their houses with boughs or rushes, mud, or sods.

Obs. The cottages of many of the poor, are still built in this manner in England: and few need travel a mile from their own residence, to see the original style of architecture.

101. Those nations which first raised the roofs of their houses on poles, were discoverers in this art. Those which first used stone, however rude, and mud or clay to fill up the interstices between the stones, and cement them together, made considerable improvements.

After the discovery of iron and metals, when the axe, the hammer, the saw, and the plane, became the tools of builders, it may be supposed, houses would soon be raised to two stories, and increased in size and convenience.

102. Burning clay into bricks, was a further invention of great importance; because, it afforded a universal material for building, as durable as stone, without carriage, and often with less labour than was required to dig and fashion the

stone.

The best bricks are made of clay, and are nine inches long, four and a half broad, and two inches and a half thick.

Obs.—Hence, in laying bricks two in breadth, with the interstices for mortar, are equal to one in length, and the requisite crosses and ties may then be made without inequalities in the wall.

103. The first cement for walls, was either mud or clay; but experiment led, in due time, to the preference of a mixture of lime, water, and sand; to which, for plastering, hair is now added. Trees presented the next building material, for beams, and boards for floors. With these materials, the

dwellings of the whole civilized world are now made.

Obs.-Cast iron for many purposes, to which timber was usually applied, has lately been used to great advantage.

104. Simple as is the contrivance of chimnies to carry off smoke, yet, they are a recent invention; and were unknown in building, till within the last five hundred years: down to that period, the smoke escaped through a hole in the roof of the house.

105. The means of letting in the light, and keeping out the cold, is also a recent invention. Anciently, holes for light were made with wooden shutters, to open by day, and close at night.

Various were the contrivances to let in light; and, at the same time, keep out cold. Bladders, horn, and membranous substances of animals and fish, were used for this purpose, in the houses of the great: but all these gave way, to the fine invention of glass.

106. That useful material was discovered by accident: some Phenician carriers of soda, a few years before Christ, happening to light their fire between some of their lumps of this mineral; it melted, and mixing with the sand, produced glass. Soda and sand, or flints, melted together, continue to be the materials of which glass is made to this day.

Obs. 1.-The manufactory of glass was long confined to Pœnicia; but so little improvement was made in it, that Nero give 60,000l. for two glass-cups that had handles. It was first applied to windows about the year 300; but did not get into general use till about 1000.

2.-A glass-manufactory is a proper object to gratify