WAIWAKAIHO BRIDGE.

Taranaki Herald, Volume XVI, Issue 790, 21 September 1867, Page 3

WAIWAKAIHO BRIDGE.

We are glad to be able to state that the re-erection of tho Waiwakaiho Bridge is advancing satisfactorily, but lest it should be supposed that very little has been done considering the length of time which has elapsed since the work was begun, we think some account of the mode of procedure Will be of interest. Most of our readers are probably aware that the main span of the bridge is to rest on four iron cylinders, which are sunk into the river bed thirteen feet below the low water line, and therefore, in all probability, be safe against the power of the heaviest freshets to undermine them. The means resorted to for sinking the cylinders are as follows : — The bed of the river is first cleared of the large stones at the spot where it is intended the end cylinder shall rest, then the foot portion of it previously built on the scaffolding is ljtvered into position, and the remaining portion of the plates built on to it, completing the length required, viz., 25 feet ; it is then securely stayed perpendicularly and weighted with some ten tons, a windlass is fixed and a ladder lowered into the interior of what appears to be an iron bound well j all is then ready for the operations of the diver. Most "of our readers have doubtlessly at some period of their lives, seen pictnres of that interesting race of people called the Esquimaux ; if one of/those sturdy individuals would only use a "go ashore" instead of a hat, he would then be not a bad imitation of a diver iv full dress — a most strange looking animal is your modern diver fully equipped for bis submarine excursions. He could be easily palmed off on the uninitiated as a rolic of the antidilttvian world, or some recently discovered amphibious animal surprised and captured by a Livingstone or a Burton, on the confines of some solitary lake in Central Africa. It would be too tedious to describe minutely the diver's dress, suffice it to say that he is enabled to remain and work below water for hours, by being clad in a water-tight dress which completely i icase3 his person — a constant supply of fresh air being pumped down to him, and the foul ailescaping through valves into the water ; he has to ba weighted with some three-quarters of a hundred weight, to enable him to sink easily — the part of the dress which covers the head is provided with three glasses which enables htm to see in clear water, but which is of very little use in the cylinders, so that all his operations have to be conducted by the sense of feeling. We will now suppose our diver under water ac the bottom of the cylinder, with his pick, shovel, and bucket* When the stuff is merely gravel and small stones, the work goes on quickly, and ho can send up some 80 buckets a day, and the cylinder gradually settles down as the interior is excavated, from ono to two feet during that period ; but when large stones lie under the edge of the cylinder it becomes a more difficult and tedious operation — they are cut off, if possible, by a long steeled bar, driven from above water and directed by the diver, and if that is not effective, then by completely undermining them 5 in case of large boulders, blasting woald have to be rasorted to. No. 1 cylinder occupied 70 hours ia sinking ten feet below tho river bed or thirteen feet below water line ; No. 2 is now in process of sinking, and is down some eight feet below/ water line > when they are lowered to the required depth they are filled with a concrete, which hardens under water to the consistency of stone. The two cylinders when braced together by heavy timbers, iron straps, and planking, will then be ready to receive the superstructure, which in the charge of Mr. Rundie, the contractor, is making rapid progress towards completion.