CII. DISCUSSION. 
Discussion. 
Mr. Burge said, there was one point he would like to mention, 
—Mr. Allan in comparing the cost of the bridge at Swan Hill 
(£8,900) with that of the bridge erected at Tocumwal (£19,635), 
gave as reasons for the saving on the former, that the plant used 
at Tocumwal was available for Swan Hill, and that the prices 
(he presumed wages was meant) were lower when the latter bridge 
was placed. Now, this comparison having been made he thought 
the qualifications should have been detailed, and he thought that 
Mr. Allan might have given a rough estimate as to the difference 
caused by the fall in wages between the two periods when these 
bridges were built, and also divided the cost of the plant. With- 
out at all events a rough idea of the qualification, the comparison 
was absolutely useless. 
Mr. Havcrorr said that he was not aware whether in this 
Colony temporary openings in bridges had been effected by other 
means than lift bridges similar to that at Swan Hill, but if such 
was not the case, he did not agree entirely with the six consider- 
ations put forward by the author which led to the adoption of the 
lift bridge at Swan Hill. : 
Taking the first of these considerations, that of economy, this 
essential could have been better secured by the adoption of a 
bascule opening with a single leaf; the economy of course Was 
confined to the cost of construction as the cost of working, though 
not the labour as measured by the work done, would be equal 1n 
either case. 
The author would no doubt acknowledge that for equal spans 
it required less power to operate a bridge of the bascule type “ 
any other kind ; the average lift of a bascule leaf being only on& 
half, or it might be, if not necessary to bring it into a vertical | 
position, one-quarter that of a straight lift bridge of equal span. — 
A bascule leaf could be constructed to operate without the aid of — 
towers by counterweighting the end, labour of opening being is 
fined to overcoming inertia and friction as in the case of a vertical 
lift bridge. He might remark that the bascule type of opemiMS 
