468 REVIEWS — EEPOET ON VICTOBIA. BEIDGE. 



to all the causes of destruction to which timber is liable, the question 

 is entirely one of finance in the supply of capital and not of dividends 

 in the future. 



By way of illustrating this question we will assume that the foun- 

 dations and masonry for abutments, piers &c, are to be the same 

 whether the superstructure is to be of wood or iron, and base 

 our calculations on a length of 5,000 lineal feet of bridge superstruc- 

 ture, varying in spans of from 50 to 250 feet which may be taken 

 to represent the bridges on a line of 300 miles. 



Basing our estimate for wooden superstructures on the known cost 

 of such works built on McCallum's patent, and which, for such spans 

 as we contemplate in this estimate, would average £S 10s. Od. Cy.per 

 lineal foot, and estimating the cost of the iron superstructure of simi- 

 lar spans at an average of £40 per foot, (that of the Victoria Bridge 

 is set dovvninMr. Boss' report at £57 Stg. = £71 5s. Od. Cy.) the fol- 

 lowing amounts will represent the first cost of each : 



5,000 feet of Timber superstructure at £8 10s. Cy. £42,500. 

 5,000 lineal feet of Irou superstructure at £40. Cy. £200,000. 

 The former at 6 per cent, would absorb an annual revenue of £2,550, 

 and the latter a revenue of £12,000. But to the first must be added an 

 amount annually sufficient to cover depreciation, repairs, risk from 

 fire, aud the cost of constaut vigilant supervision, which would perhaps 

 be not less than 15 per cent, per annum, and under some circumstances 

 might amount to 20 per cent, these contingencies not being applica- 

 ble to the iron superstructure would bring the annual charge for the 

 wooden bridge up to £3,925 Cy. being within £3,075 of the like charge 

 for the more desirable one ; a difference, however, which being capi- 

 talized, will represent an item of upwards of £50,000 in the capital 

 account. It is difficult therefore to resist the conclusion that the 

 introduction of Iron Railway Bridges into this country is prema- 

 ture. 



The enhanced cost above indicated is still more apparent if we 

 apply the comparison to the Victoria Bridge. Spans of the 

 dimensions adopted in that work have frequently been executed 

 in wood in the most reliable manner at a cost of $35 per foot ; 

 and with every provision against fire, for protection against the 

 weather, for ventilation, &c, the cost would not exceed $45 or 

 £1.1 5s. Cy. the whole cost of the 7,000 feet which Mr. Ross esti- 

 mates in iron at £400,000 would not therefore exceed £78,750 Cy. it 

 would consequently be cheaper to build in wood even if it demanded 

 an entire renewal every Jive years. Mr. Stephenson, however, has 

 dismissed all thought of a wooden superstructure in a very summary 



