XXXII. H. D WALSH. 
The leading objects to be considered in planning a wharf 
or a jetty, are sufficient deck area in relation to berthing 
space, combined with requisite strength and economy of 
cost. The earning power of a wharfis governed chiefly by 
two things: (a) the length of berthing space, (b) the capital 
cost; and itis in a proper adjustment of these two elements 
to one another, that the skill and forethought of the 
engineer become manifest. The commercial value of 
wharves and jetties in any part of the world can be fairly 
well compared on this basis. Regarding the cost of timber 
wharves and jetties per lineal foot and per square foot, no 
reliable rule can be laid down, as so much depends on the 
conditions of the foreshore, the amount of dredging, rock 
excavation, depth of the water, and the materials used. 
Piles.—In timber wharf constructions the first consider- 
ation is a selection of the piles. This of course brings up 
the question of protection against marine borers. Sheathing 
with yellow metal, which practically doubles the cost of 
the piles, has not been so successful in point of durability, 
in recent years as it used to be, as I shall presently show. 
Nearly all the old private wharves from the head of Darling 
Harbour to Circular Quay were built of unsheathed turpen- . 
tine piles of from 8 inches to 12 inches diameter. Though 
the exact dates of erection in some instances are not 
obtainable, the majority of them had been standing about 
30, and one or two even 40 years. They were generally 
of light construction, having been built to suit the require- 
ments of the time. It is interesting to note, that had it 
not been for the great increase in tonnage of ships in recent 
years, several of these old wharves might have been 
repaired and made serviceable for a few years more. 
Naturally some of the many piles drawn were found to be 
entirely crippled, but an examination showed that such 
were usually not turpentine timber. 
