m 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.
[1] Mr. Milne.

LETTER III.

Sir, Dec. 15,1759.

It is the common fate of erroneous positions, that they are betrayed by
defence, and obscured by explanation; that their authors deviate from
the main question into incidental disquisitions, and raise a mist where
they should let in light.

Of all these concomitants of errours, the letter of Dec. 10, in favour
of elliptical arches, has afforded examples. A great part of it is spent
upon digressions. The writer allows, that the first excellence of a
bridge is undoubtedly strength: but this concession affords him an
opportunity of telling us, that strength, or provision against decay,
has its limits; and of mentioning the monument and cupola, without any
advance towards evidence or argument.

The first excellence of a bridge is now allowed to be strength; and it
has been asserted, that a semi-ellipsis has less strength than a
semicircle. To this he first answers, that granting this position for a
moment, the semi-ellipsis may yet have strength sufficient for the
purposes of commerce. This grant, which was made but for a moment,
needed not to have been made at all; for, before he concludes his
letter, he undertakes to prove, that the elliptical arch must, in all
respects, be superiour in strength to the semicircle. For this daring
assertion he made way by the intermediate paragraphs, in which he
observes, that the convexity of a semi-ellipsis may be increased at will
to any degree that strength may require; which is, that an elliptical
arch may be made less