A Treatise On The Principles And Practice Of Harbour Engineering

152 HARBOUR ENGINEERING. opérations than, at anyrate, can be gnaranteed by the barge system. Interruptions of more than a few hours’ duration during tempestuous weather occur but rarely, and there is little time lost in waiting for the subsidence of the sea after a storm has spent its force. Of course, this assumes that the staging itself suffers no appreciable damage. It cannot be deuied that temporary structures of slender build exposed to the full force of a gale run some risk of destruction—partial, if not complète. Collapses of greater or less extent have proved this beyond question, yet the instances are not so numerous as to warrant the attachment of very serious importance to the objection, and the particulars are not infrequently exaggerated. Thus, writing in 1904, Sir William Matthews, K.C.M.G., says: — “ Notwithstanding the alarming reports which have appeared in the press, from time to time, with regard to the works at Dover, it is satisfactory to state that practically uo damage whatever, from the first, has been occasioned Fra. 125. Longitudinal Elevation of Staging, Holyhead Breakwater. to the permanent works, and only comparatively insignificant damage, having regard to the magnitude of the undertaking, has been caused to the temporary structures. Although it was alleged that during the great gale in September 1903 one thousand feet of breakwater works and staging had been carried away> the only loss which was occasioned was the turning over of one span of temporary staging of 50 feet in length with the plant thereon, which, at that time, occupied an isolated position.” 1 A more serious source of danger to sea staging is insect attack, and it is the more to be feared in that the depredations of sea-worms may remain undetected for some time. Constant inspection, therefore, is absolutely essential, and there can be no feeliug of security. We are dealing, however, with this matter more at length in another section. Apait from these drawbacks, staging forms a steadier base for working purposes than a barge or vessel. Platforms may be affixed to it, or suspended 1 Matthews on Harbours of Great Britain, Trans. Am. Soc. C.E., vol. liv.