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Considerations On The Plans Offered For The Construction Of Blackfriars Bridge
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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 told that one of the judges appointed to decide this question, is Mr. M–ll–r, 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 publick, 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.
LETTER II.
Dec. 8, 1759.
SIR,
In questions of general concern, there is no law of government, or rule of decency, that forbids open examination and publick discussion. I shall, therefore, not betray, by a mean apology, that right which no man has power, and, I suppose, no wise man has desire to refuse me; but shall consider the letter published by you last Friday, in defence of Mr. M—-‘s[1] 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.
The iron rail, whether gilt or varnished, appears 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 loath that our own country should unite two follies in a publick work.
The architrave of Perrault, 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.