has each rib made up of three I-shaped segments bolted together and united transversely; the span is 100 feet in each of the three openings, and the ribs are three feet deep at the springing, diminishing about six inches at the crown. We have yet to learn why engineers have abandoned the arched bridge for the wrought iron girder system, except that the latter is considered more economical, and better fitted for bearing tensile stress. Cast-iron bridges constructed as rigid arches, subject to compression and composed of small parts, have all the mechanical advantages of stone without some of its drawbacks, while artistically they can be made satisfactory erections.--_Building News_. * * * * * SIR W. PALLISER. We announce with regret the death of Major Sir William Palliser, which took place suddenly on February 4, 1882. Sir William had been suffering from disease of the heart for a considerable period, but we believe that no one anticipated that the end was so near. For some twenty years Sir William had devoted himself to the improvement of guns, projectiles, and armor. To him is attributed the invention of the chilled-headed projectiles which are known by his name. There seems to be no doubt that chilled projectiles were suggested at Woolwich Arsenal, and even made, before Sir William took the matter up, but there is excellent reason to believe that Sir William knew nothing of this, and that the invention was original with him; at all events, he, aided by the efforts of the foundry and the laboratory at Woolwich, brought these projectiles to perfection, and unless steel-faced armor defeat them they cannot be said to have as yet met their match. A most valuable invention of the deceased officer was the cut-down screw bolt for securing armor plates to ships and ports. It was at one time feared that no fastening could be got for armor plates, as on the impact of a shot the heads or the nuts always flew off the bolts. The fracture usually took place just at the point where the screw-thread terminated. Sir William adopted the bold course of actually weakening the bolt in the middle of its length by turning it down, so that the screw stands raised up instead of being cut into the bolt, and by this simple device he changed the whole face of affairs, and the expedient applied in other ways, such as by drilling holes longitudinally down bolts, has since been extensively adopted where great immunity from fracture is required.