The Evening Star MONDAY, JANUARY 10, 1870

Evening Star, Volume VIII, Issue 2084, 10 January 1870, Page 2

The Evening Star MONDAY, JANUARY 10, 1870

The letter of a correspondent, published in another column, directs attention to a very important feature of public expenditure—that of civil engineering. The memorable flood of two years ago pointed to grave mistakes in the position and construction of many bridges. Attention was called to them by the public Press, but the Press apparently is treated as if it wore merely an engine of political strife, instead of the means of pointing to defects in our public arrangements, and of correcting them. It is not pleasant, as public writers, to have to And fault where the character or ability !of individuals is concerned. It would be far more agreeable to have to aid in the general pi’Ogress than to be the : censor of departmental blunders. It would be a, far more grateful task to have been able to point with pride to istructures that had stood the test of time and flood, than to have had to condemn them as expensive failures. But so far as our roads and bridges are concerned, truth compels us to say there has been evinced a total misapprehension of the adaptation of means to ends. There is not a Colony in Australasia that lias had such expensive abortions as have been witnessed in Otago, nor in which there appears to have been the same persistence in constructions proved by experience to have been faulty in principle. We do not think anywhere in the Southern Colonies, the Governments have . shown themselves equal to apprehending the advanced applications of the day. This may in part be accounted for by the inability of non-scientiflc men to judge correctly of the plans laid before them. They are therefore liable at all times to put faith in any man who comes recommended from Home, or elsewhere. We see this tendency in General, Provincial, and Civic Governments, and it seems to have taken inveterate root in Otago, as is proved by our want of success in gas and water works, roads and bridges. We do not accept as true the axiom, By their worksyou shall know them. That doctrine is too sound and practical for Otago, whose statesmen, unfortunately for the Province, are too prone to sacrifice public interest to personal feeling. The consequence is that our public works cost many times more than they ought to cost through our having to re-make them or patch them up to keep them serviceable. One of the most obvious principles in bridge building is to give as free a course as possible to the stream of water over which the bridge is built. It requires no engineering skill to know that. Nor does it require any stretch of reason to understand that, in order to secure this disideratum, there must be as few impediments in the water way, in the shape of piers and piles, as possible. Were the fine passage of water the only requirement, this precaution should be obviously observed ; but when in addition to that, timber or other material is liable to be swept down bv the current, to get foul of the supports and to pile up obstructions there, that ultimately form a dam and entail a pressure on the bridge it is not able to resist, there can be but one result—the bridge is swept away or so shaken as to become useless. We have instance upon instance of this folly. At Waikouaiti, through that cause alone, the bridge was swept away two years ago. It has been restored exactly as before. At the Water of Leith the old bridge was rendered useless from the same cause. Another has been erected in which the evil is intensified. The Taieri Bridge has become useless from that and other defects, and plenty of instances might be pointed out where precisely the same want of foresight has been shewn. Had these been the first attempts at bridge building in the world, the mistakes would have been excusable ; but there is scarcely any science better understood than that. Gould it even have been said that economy had been kept in view in adopting that form of structure, some faint excuse might been made. But oven that fails, for in other Colonies bridges are thrown across wider streams than the Water of Leith, the Waikouaiti, or the Taieri, at very much less expense, and without offering any obstruction to the free passage of the current. Those bridges are common enough in Great Britain and the Continent, with arches of sufficient span to allow any material whatever to pass beneath them freely. Over the Deo. at Chester, there is an arch of 200 feet span. Over the Dora, at Turin, the single-arched bridge lias a span of UG feet 6 inches. The Gloucester iron bridge lias an elliptical arch of 150 foot, and numerous instances could be given of railway bridges whore the arches span 100 to 1 GO feet. Nor need it bo said that the cost of these works is above the ability of the Province to sus-

tain. In Victoria a jingle avch was tli«pw^ r across tlie Yarra, at Stuclley PaM, at expense...ol a couple of thousand, poilnds, ?nd because on account hfy the arches being above the bridge, tiiey found inconvenient for traffic, "‘they were replaced by a single arch below by a millwright named Bates, at an expense of under one thousand • pounds. In Bngland cheap and durable arches, with immense spans, are formed on railway lines by planks bolted together , and modifications of suspension bridges are to be found in various places which fully serve the purpose. We throw out these suggestions to draw public attention to the fact that in our appliances wo are behind the age ; and if wo are to put our revenues to the best use, we must get out of the groove we have hitherto run in.