399

THE Plans which have been offered by different architects, of different reputation and abilities, for the construction of the Bridge intended to be built at Black-Friars, are, by the rejection of the greater part, now reduced to a small number; in which small number, three are supposed to be much superior to the rest; so that only three architects are now properly competitors for the honour of this great employment; by two of whom are proposed semicircular, and by the other elliptical arches.

The question is, therefore, whether an elliptical or semicircular arch is to be preferred?

The first excellence of a bridge built for commerce over a large river, is strength; for a bridge which cannot stand, however beautiful, will boast its beauty but a little while; the stronger arch is therefore to be preferred, and much more to be preferred, if with greater strength it has greater beauty.

left by a wedge driven between them. In proportion as the stones are wider at the top than at the bottom, they can less easily be forced downwards, and as their lateral surfaces tend more from the centre to each side, to so much more is the pressure directed laterally towards the piers, and so much less perpendicularly towards the vacuity.

Upon this plain principle the semicircular arch may be demonstrated to excel in strength the elliptical arch, which approaching nearer to a straight line, must be constructed with stones whose diminution downwards is very little, and of which the pressure is almost perpendicular.

It has yet been sometimes asserted by hardy ignorance, that the elliptical arch is stronger than the semicircular; or in other terms, that any mass is more strongly supported the less it rests upon the supporters. If the elliptical arch be equally strong with the semicircular, that is, if an arch, by approaching to a straight line, loses none of its stability, it will follow, that all arcuation is useless, and that the bridge may at

laid in straight lines from pillar to pillar. But if a straight line will bear no weight, which is evident at the first view, it is plain likewise, that an ellipsis will bear very little; and that as the arch is more curved, its strength is increased.

ness.

All arches have a certain degree of weakNo hollow building can be equally strong with a solid mass, of which every upper part presses perpendicularly upon the lower. Any weight laid upon the top of an arch, has a tendency to force that top into the vacuity below; and the arch thus loaded on the top, stands only because the stones that form it, being wider in the upper than in the lower parts, that part that fills a wider space cannot fall through a space less wide; but the force which laid upon a flat would press directly downwards, is dispersed each way in a lateral direction, as the parts of a beam are pushed out to the right and

Having thus evinced the superior strength of the semicircular arch, we have sufficiently proved, that it ought to be preferred; but to leave no objection unprevented, we think it proper likewise to observe, that the elliptical arch must always appear to want elevation and dignity; and that if beauty be to be determined by suffrages, the elliptical arch wil have little to boast, since the only bridge of tha kind has now stood two hundred years without imitation.

If in opposition to these arguments, and in defiance at once of right reason and general authority, the elliptical arch should at last be chosen, what will the world believe, than that some other motive than reason influenced the determination? And some degree of partiality cannot but be suspected by him, who has been

old that one of the judges appointed to decide this question, is Mr. M―ll, who having by ignorance, or thoughtlessness, already preferred the elliptical arch, will probably think himself obliged to maintain his own judgment, though his opinion will avail but little with the public, when it is known that Mr. S-ps-n declares it to be false.

He that in the list of the committee chosen for the superintendency of the bridge, reads many of the most illustrious names of this great city, will hope that the greater number will have more reverence for the opinion of posterity, than to disgrace themselves, and the metropolis of the kingdom, in compliance with any man, who, instead of voting, aspires to dictate, perhaps without any claim to such superiority, either by greatness of birth, dignity of employment, extent of knowledge, or largeness of fortune.

In questions of general concern, there is no law of government or rule of decency, that forbids open examination and public discussion. I shall therefore not betray, by a mean apology, that right which no man has power, and, I suppose, no wise man has desired to refuse me; but shall consider the Letter published by you last Friday, in defence of Mr. M-'s* design for a new bridge.

Mr. M- — proposes elliptical arches. It has been objected that elliptical arches are weak and therefore improper for a bridge of commerce, in a country where greater weights are ordinarily carried by land than perhaps in any other part of the world. That there is an elliptical bridge at Florence is allowed, but the objectors maintain, that its stability is so much doubted, that carts are not permitted to pass over it.

To this no answer is made, but that it was built for coaches; and if it had been built for carts, it would have been made stronger: thus all the controvertists agree, that the bridge is too weak for carts; and it is of little importance, whether carts are prohibited because the bridge is weak, or whether the architect, knowing that carts were prohibited, voluntarily constructed a weak bridge. The instability of the elliptical arch has been sufficiently proved by argument, and Ammanuti's attempt has proved it by example.

pears to me unworthy of debate. I suppose every judicious eye will discern it to be minute and trifling, equally unfit to make a part of a great design, whatever be its colour. I shall only observe how little the writer understands his own positions, when he recommends it to be cast in whole pieces from pier to pier. That iron forged is stronger than iron cast, every smith can inform him; and if it be cast in large pieces, the fracture of a single bar must be repaired by a new piece.

The abrupt rise which is feared from firm circular arches, may be easily prevented, by a little extension of the abutment at each end, which will take away the objection, and add almost nothing to the expense.

The whole of the argument in favour of Mr. M-, is only that there is an elliptical bridge at Florence, and an iron balustrade at Rome; the bridge is owned to be weak, and the iron balustrade we consider as mean; and are loth that our own country should unite two follies in a public work.

The architrave of Perault, which has been pompously produced, bears nothing but its entablature; and is so far from owing its support to the artful section of the stone, that it is held together by cramps of iron; to which I am afraid Mr. M- must have recourse, if he persists in his ellipsis, or, to use the words of his vindicator, forms his arch of four segments of circles drawn from four different centres.

That Mr. M— obtained the prize of the architecture at Rome, a few months ago, is willingly confessed; nor do his opponents doubt that he obtained it by deserving it. May he continue to obtain whatever he deserves; but let it not be presumed that a prize granted at Rome, implies an irresistible degree of skill. The competition is only between boys, and the prize given to excite laudable industry, not to reward consummate excellence. Nor will the suffrage of the Romans much advance any name among those who know, what no man of science will deny, that architecture has for some time degenerated at Rome to the lowest state, and that the Pantheon is now deformed by petty decorations. I am, Sir, yours, &c.

Mr. Mylne.

and raise a mist where they should let in light. Of all these concomitants of errors, the Letter of Dec. 10th, in favour of elliptical arches, has

without this supply, would have been in danger of perishing by famine. Rome actually saw herself reduced to this condition under Augustus; for there remained only three days' provision of corn in the city; and that prince was so full of tenderness for the people, that he had resolved to poison himself, if the expected fleets did not arrive before the expiration of that time; but they came; and the preservation of the Romans was attributed to the good fortune of their emperor; but wise precautions were taken to avoid the like danger for the future.

Though mines of gold and silver should be exhausted, and the species made of them lost; though diamonds and pearls should remain concealed in the bowels of the earth, and the womb of the sea; though commerce with strangers be prohibited; though all arts which have no other object than splendour and embellishment, should be abolished; yet the fertility of the earth alone would afford an abundant supply for the occasions of an industrious people, by furnishing subsistence for them, and such armies as should be mustered in their defence. We, therefore, ought not to be surprised, that agriculture was in so much honour among the ancients for it ought rather to seem wonderful that it should ever cease to be so, and that the most necessary and most indispensable of all professions should have fallen into any contempt.

Agriculture was in no part of the world in higher consideration than Egypt, where it was the particular object of government and policy: nor was any country ever better peopled, richer, or more powerful. The Satrapa, among the Assyrians and Persians, were rewarded, if the lands in their governments were well cultivated; but were punished, if that part of their duty was neglected. Africa abounded in corn, but the most famous countries were Thrace, Sardinia, and Sicily.

Cato, the censor, has justly called Sicily the magazine and nursing mother of the Roman people, who were supplied from thence with almost all their corn, both for the use of the city, and the subsistence of her armies: though we also find in Livy, that the Romans received no inconsiderable quantities of corn from Sardinia. But, when Rome had made herself mistress of Carthage and Alexandria, Africa and Egypt became her store-houses: for those cities sent such numerous fleets every year, freighted with corn, to Rome, that Alexandria alone annually supplied twenty millions of bushels: and, when the harvest happened to fail in one of these provinces, the other came in to its aid, and

sup

When the seat of empire was transplanted to Constantinople, that city was supplied in the same manner; and when the emperor Septimius Severus died, there was corn in the public magazines for seven years, expending daily 75,000 bushels in bread, for 600,000 men.

The ancients were no less industrious in the cultivation of the vine than in that of corn, though they applied themselves to it later for Noah planted it by order, and discovered the use that might be made of the fruit, by pressing out and preserving the juice. The vine was carried by the offspring of Noah into the several countries of the world: but Asia was the first to experience the sweets of this gift; from whence it was imparted to Europe and Africa. Greece and Italy, which were distinguished in so many other respects, were particularly so by the excellency of their wines. Greece was most celebrated for the wines of Cyprus, Lesbos, and Chio; the former of which is in great esteem at present: though the cultivation of the vine has been generally suppressed in the Turkish dominions. As the Romans were indebted to the Grecians for the arts and sciences, so were they likewise for the improvement of their wines; the best of which were produced in the country of Capua, and were called the Massick, Calenian, Formiau, Cæcuban, and Falernian, so much celebrated by Horace. Domitian passed an edict for destroying all the vines, and that no more should be planted throughout the greatest part of the west; which continued almost two hundred years afterwards, when the emperor Probus employed his soldiers in planting vines in Europe, in the same manner as Hannibal had formerly employed his troops in planting olive trees in Africa. Some of the ancients have endeavoured to prove, that the cultivation of vines is more beneficial than any other kind of husbandry: but, if this was thought so in the time of Columella, it is very different at present; nor were all the ancients of his opinion, for several gave the preference to pasture lands.

The breeding of cattle has always been considered as an important part of agriculture. The riches of Abraham, Laban, and Job, con