Chapter VI. Of Metals

THE metals commonly employ’d in buildings, are iron, lead, and copper. Iron serves to make nails, hinges, bars, gates, bolts for fastenings, and such like works.

THERE Is no iron any where found pure; nor any, when taken out of the earth, but must first be melted, and ‘then urged of its dross by the fire, to make it fit for use. For then it will easily be made red-hot, will be soft enough tobe wrought, and spread under the hammer; but cannot so easily be melted again, except it is put into a furnace made for that purpose: And if not well hammer'd when red-hot, it will burn and ate away.

IT is sign the iron is good, if, when reduced into bars, you see the veins run straight and uninterrupted, and that the ends of the bars be clean and without dross: For these veins will shew that the iron is free from lumps and flaws; by the ends we may know the guodnefy of the middle; and, when wrought into square plates, or any other shape, if its sides are straight and even, we may conclude it is equally good in all its parts, as it has equally in every part endured the hammer,

MAGNIFICENT palaces, churches, towers, and other publick edifices, are generally covered with lead. The pipes and gutters to convey the water, are also made of the same, It likewise serves to fasten the hinges und iron-work in the jambs of doors and windows, The three sorts of lead usually found, are the white, black, und that of a colour between boh, by some called at-colour. “The black is so called, not because it is really such, but because it is intermix'd with some blackness; therefore the antients, to distinguish it from the white, gave it very properly that name. The white is much more perfect, and of greater value than the black. “And the at-colour holds the middle rank betwixt both,

Leap is either taken out of the earth in a great mass, without any mixture, or in finall, shining, blackish lumps; and is sometimes found sticking in small flakes to the rocks, to marble, and tu stones. All the different sorts melt very easily, because the heat of the fire liquifies it before it can he made red-hot; and if thrown into an extreme hot furnace, it will not preserve its substance, but be converted into litharge and dross. Of the three sorts the black is the softest and most weighty, and therefore will easily spread under the hammer. "The white is harder and lighter, The ash-colour is much harder than the white, and is of a middle weight between both,

Publick buildings are sometimes cover'd with copper; and the antients also made nails and cramps thereof, which were six’d in the stone below, and to that above, to unite and tie them together, and prevent them from being pushed out of their place. And by means of these nails and cramps, a building, which can’t possibly be made without a great number of pieces of stone, is so join'd and six’d together, that jt appears to be one entire piece, and for the fume reason is much stronger and more durable.

These nails and cramps were likewise made of iron; but the antients most commonly made them of copper, because it is less subject to rust, and consequently will last much longer. The Letters for inscriptions, that were placed in the frizes of buildings without, were made of copper; and history informs us, that the hundred famous gates of Babylon, and Hercules two pillars, eight cubits high, in the island of Gades, were alto made of that metal,

The best and most excellent copper is that which is extracted and purged from the ore by fire. If it is of a red colour, inclining to yellow, well-grained, and full of pores, we may then be pretty certain it is freed from dross.

Copper will heat red-hot in the fire, like iron, and so liquify that it may be cat. If thrown into an extreme hot furnace, it will not endure the flames, but totally consume and + waste away. Although it be hard, it will nevertheless bear the hammer, and may be wrought into very thin plates. The best method to preserve it is to dip it into tar; for tho’ it does not rust like iron, yet it has a peculiar rust, called verdigreafe, especially if it be touched with any sharp liquor.

The 1s metal mix’d with tin, lead and brass (which last is only copper coloured with lapis calaminaris) makes bronze, or bell-metal, which is often used by architects in making bales, columns, capitals, statues, and such-like ornaments. There are to be seen in the church of St. Giovanni Laterano in Rome four brass columns (one of which only has its capital) mads by the order of Augustus of the metal that was found in the prows of those snips he had taken in Egypt from MARK ANTHONY,

There allo remains in Rome to this day four antient gates; viz. the Rotunda, formerly the Pantheon; that of St. Adriano, formerly the temple of Saturn; that of St. Cosmo and St. Domiano, formerly the temple of Castor and Pollux, or rather of Romulus and Remus; and that of St Agnus, now called St. St.aghefe, without the gate Fiminalis fit la via Numenta,

THE most beautiful of these is that of Santa Maria Rotunda wherein the antients ende-cured to imitate by art that sort of Corinthian metal in which the natural colour of gold did mostly predominate: For we read, that when Corinth, now called Coranto, was burnt and destroy’d, the gold, silver, and copper were melted and united into one mass, which was so temper'd and mix’d together, that it composed the three sorts of brass afterwards called Corinthian. In the first, silver prevailed, of which it retained the whiteness and lustre; the second, as it partook more of the gold, retained mostly its yellow colour; the third was that in which all the three metals were pretty equally mix’d. All these have afterwards been imitated by various workmen.

Having sufficiently explained the several particulars and materials most necessary to be consider'd and prepared before we begin to build; it is proper, in next place, to say something of the foundations, since it is from them the whole work must be raised.