E.—2

4

Again, the anchor-plates differ from the drawings in two particulars: First, the holes in the original drawings are in no case opposite one another on the two sides of the weh; hut in two cases in the casting these holes are nearly opposite ; and it was just at these points that the anchors gave way. Secondly, the holes were designed to be directly in the line of the strain, and perpendicular to the face of the flange ; but some of them, especially where the fracture occurred, are a good deal out of the true line; and as the holts filled the holes, an appreciable cross strain was brought on the metal, tending to throw it still further into tension. We do not consider that any responsibility can be thrown on the contractors. There are no provisions in the contract as to the quality of metal to be used, or that any test should be applied to prove their strength. They were to be made to the satisfaction of the Engineer; and they were accepted as sufficient after examination; nor, if the intention of the Chief Engineer had been carried out, and the anchor-plates supported by the concrete or masonry, so that these plates would be only doing the work of washers, would blame attach anywhere. The accident must be attributed solely to the misunderstanding of the instructions given as to the time Avhen the tunnels were to be built up. But if it had been contemplated that the anchor-plates, on which the whole stability of the structure rested, until backed by the concrete, were to bear even for a short time the whole strain, we should consider that insufficient care had been taken to secure the strength of those beams. Little appears to have been done to secure good castings. A large casting, when cold, has its particles left in a state of permanent tension, so that even a sharp frost may shatter a very granular mass of cast iron. Engineers in England increase the toughness of the metal by addition of scraps of malleable iron. The practice recommended in England to secure a good mixture of iron, in contracting for a number of girders, is to stipulate that they should not break with less than a certain weight, leaving the mixture to the founder. The Engineer may then select one to be broken, and if it break with less weight than that agreed upon, the whole may be rejected. This test could not conveniently be used in the case of these massive anchor-plates; but the Resident Engineer might have been instructed to see that the pig, when put into the cupola, was mixed with a fixed proportion of malleable iron. He should also have taken care that the pattern was in accordance with the design, and that the mould was in the proper position. We have the honor to be, Sir, Your most obedient Servants, Jambs Edward EitzGerald. Charles C. Knigiit.