242 DISCUSSION ON 
bridge would cost for one hundred and twenty feet span £3,000 
including painting. Assuming the life of a steel bridge at one 
hundred and fifty years and taking interest at four per cent. the 
annual charge for interest, sinking fund and maintenance would 
be £150. The total cost of timber superstructure for one hundred 
and twenty feet span would be £1,870 for a truss bridge twenty- 
feet deep with twelve feet panels. Assuming the life of the iron 
work at one hundred and fifty years, and taking the life of the 
timber work at twenty-five years and interest as before at four 
per cent. the annual charge for interest, sinking fund and main- 
tenance would be £125. In connection with the timber bridge 
it might be noted that provision only had been made for the 
liquidation at the end of twenty-five years, of the prime cost of 
the timber work and re-erection of iron work, the whole of the iron 
work being again utilised when timber superstructure was replaced 
at the end ofits life. To recapitulate, the steel superstructure of 
one one hundred and twenty feet span would cost £3,000 as 
against £1,870 for a timber superstructure, or a saving in prime 
cost in favour of the timber bridge of £1,130 whilst the charge 
against revenue by the adoption of the timber bridge—after allow- 
ing for sinking fund—would be reduced from £150 to £125 per 
annum. Ifa saving of 37-7 per cent. could be effected in the 
prime cost, and 16-7 per cent. in the annual charge against revenue 
when timber had to be carried two hundred miles by water and 
three hundred miles by rail, how much more noticeable would this 
saving be when timber was in abundance close at hand. 
Mr. G. FiscHer considered that the paper might be divided - 
into two portions, viz., a way was indicated how a cheap standard 
gauge railway ‘could be constructed in New South Wales, and 
secondly, the author gave his reasons why he objects to a break 
of gauge. He could not agree with the author in the means 
employed to make a saving in first cost, by spacing the sleepers 
about three feet six inches centres, and putting only three inches — 
-of ballast under them. It was no doubt all correct according to 
-calculations, but he considered that in practice it would not give 
