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98 THE CIVIL ENGINEER AND ARCHITECT’S JOURNAL. [March, Me a correspondent as myself, will be allowed to add much weight to the criticism of Mr. Leeds; nor should I venture on these remarks, hut that opinions—and very decided ones—have been expressed by so many persons, whose right to pass sentence is not more than mine. The defects of the structure should have been criticised with a more candid reference to the imperative necessities which interfered with the full exercise of the architect’s taste;.and the merits of the portico (particularly as regards its plan) of the entrance hall, and of the general proportions of the several compartments of the facade, separately considered, should have been allowed. Granted, the central cupola is small, its tambour much too plain, anil the two smaller cupolas or turrets unnecessary. The cornice of the portico, too, cer tainly lacks that prominence and richness which the Corinthian columns (particularly as they are fluted) require; but the pirtico otherwise, in regard to its low-pitched pediment (perhapsit may he too low) and the just approximation of its columns, is worthy of infinitely more admiration than the St. Martinians have yet bestowed upon it ; a i d I "ordially ajree with the writer, whose minute ana ysis wou d itnder any further comments gratuitous, that the “ faca h*, if erected some years earlier, would have been probably as much extolled as it has now been decried.” My chief purpose in now addressing you, is tosngg-st such remedial measures as I conceive to he—at a verv little expense—practicab'e ; and 1 therefore, witli all deference (as to an unquestionable superior whom, in spiteof the world, I delight to honour) submit to the archi tect the adjoined sketch, simply showing how, hy raising attic stories over the central and extreme compartments ; by transposing the columns now in the centre of the wings, and hy placing a pilaster attic order round the tambour of the dome, an altered effect would be pro duced, which the public might deem an improvement. The dome will still perhaps remain too small (the dotted line inclosing it being more accordant with my own notions of proportion), but it will certainly not be so objectionable on the score of plainness. If the dome could be entirely reconstructed, it might possiblv be made at once available, for increased accommodation and effect; but I am speculating only on what may be gathered from the small engravings before me, anil saw' too little of the building when in London some time back, to ven ture on anything more than mere suggestions. Your obedient servant, GEORGE WiGHTWICK. Plymouth, Feb., 1839. [We regret that it is out of ottr power to comply with the request of our correspondent as to the insertion of a wood-cut, as it would form a precedent which would not fail in other cases of suggestions to entail on us great inconvenience and expense. We think his proposed alt 1 ra tions would be calculated to produce the effect lie describes, hut they would have a tendency to alter the character of the building front its present classicality.]—Edit. Civ. Eng. §• Arch. Journal. RAILWAY CURVES. Sm,—Having been lately employed setting out railway curves, like your correspondent, “A Sub” (in your January number), I cannot help offering a few observations on his plan ; although I fear 1 am not one of the “ more experienced readers” that he expected would take it up. He says, he thinks “ it would be an improvement upon the system of running directly from a straight line to a curve of 1 j, 2, or 2) miles radius, if a curve of 3, 4, or 5 miles radius, for a short distance, were made use of to connect them.” Now to me it appears that the true principle is this :—When you must change your line of direction in a railroad, do so with ns.equable a curvature as possible ; for we know that if the curvature is not equa ble, some parts of it must be sharper than if the same radius were used all through. This, I think, would be a sufficient reason for rejecting his plan at the outset. But even if without injury we could have a gradual increase of curvature—Cut bono ? Is it to accustom the engines to a curvilinear path ? Surely when an engine is at a point just entering on a curve, it is pretty clear that its action on that curve will not be affected by the nature of the path it was preciously describing, since its tendency just then is in the direction of the tangent, which is quite independent of that path. Again, your correspondent says, “ that projectiles (where the resistance is equal) assume the parabolic curve,” by which lie pro poses an approximation. Now the resistance being constant is not the cause of a projectile’s describing a parabola, but because gravity, which acts upon it, is a constant force, producing a constantly accelerated velocity, so that the distances gone in a vertical direction are as the squares of those gone in a horizontal (counting from the highest point), which is not a very similar case to that of an engine moving along a railway. But even if we were to draw an inference from the motion of a projectile, I would do it tints :—We know that the curva ture of its path is not constant, neither is its velocity—the latter being least when the former is greatest; now, the velocity of an engine should be constant, if possible—therefore, let the curvature of its path be so also.— I remain, Sir, your most obedient servant, Feb. 19, 1839. R. W. T. A METHOD FOR STRIKING GOTHIC ARCHES. Sir,—I beg leave to make public, through the medium of your Journal, the following method, which I discovered some years ago, and which I believe to he original, for Striking Gothic Arches, more particularly that which lias been termed the Tudor arclt:— Having determined the height and breadth of the arch, draw a horizontal line on a whitened wall ; make the length of this line twice the height of the arclt, and from the centre of the line, let fall a perpen dicular, to which give one half the widtlt of the arch. Let nails be driven at tile two extremities of the horizontal line ; to one of these fix an end of a chain somewhat heavy, but composed of short links, and, passing the other end over the other nail, draw up the chain till the bottom of tlte curve correspond with the extremity of the perpendicular, and when in that position make the chain fast to tlte nail over which it was passed. This done, trace upon tlte wall, with charcoal or other wise, one half of the curve formed by tlte freely suspended chain. This curve, placed in suclt a manner as that tlte lower or more curved part may rest upon tlte impost, will form one half of tlte required Tudor arch, the other half being its counterpait—thus :— Fig. 1. C Mg- 2- of E F, let fail G = hA? Tlte chain being fastened at E, and then 2. passed over F, and drawn up until tlte bottom of the curve correspond with II, make fast at F. Now tlte curve E II or F II placed so as that tlte more curved part fall on tlte impost; and tlte extreme E or F at tlte point C (fig 1), will be half of the required Tudor arclt. By this bisection and arrangement of a Catenary, gothic arches of various agree able curvature may be most easily and expeditiously traced. I am, Sir, vottr most obedient, 13th Feb. 1839. J. R. JACKSON, Col. [We have taken tlte liberty of altering our correspondent’s arrange ment of tlte figures, by making two answer the purpose of three, which we hope lie will excuse, particularly as it does not interfere with the description of his ingenious and simple method of setting out the art'll ; a method which, we are sure, will be appreciated by tiie profession.— Editor.] MONTROSE WET DOCK. Report of James Walker, Esq., Civil Engineer. The Site.—Having visited Montrose, in company with Mr. Leslie, early ill December last, I surveyed the sites and plans of Docks proposed by that engineer, viz.,—the Horologe Hill site, and the other between Meridian Place and tlte patent Slip, or farther down the river than the Horologe Hill; and I have no hesitation in preferring tlte lower situation. It places the entrance in a wider and better part of the liver, where the eddy-tide will render the entering of the ships very easy ; it interferes less with the present wharfage ; and (which I think very important) gives the opportunity of extending the Docks as occasion may require upon the links—a property which is uncovered and belongs to the town. I consider this site also, whether ns respects ap proach from sea, entrance to the Dock, or the Dock itself, peculiarly eligible. First, as to the approach prom Sea,—Having had reference to an apparently very accurate survey by Mr. Buchanan of Edinburgh, and having