Bram.— On the Building Materials of Otago. 127 
example which I noticed lately exists in the masonry of the Waitaki Bridge, 
erected in 1869; although apparently well proportioned and prepared, the 
mortar in some places is still no harder than stiff clay. There is no greater 
anomaly in the constructive arts than what is displayed in the use of weak 
mortar with strong bricks. We might as well connect plate iron with lead 
rivets. In designing a bridge or a roof every part is strained alike, so 
there is nothing wasted; but in the case before us, three-fourths of the 
work is thirty times stronger than the remainder. As shown above, the 
cost of increasing the strength of our mortars five times is 3d., and ten 
times 9d. per cubic yard of brickwork. These figures would only represent 
£10 and £80 on the new telegraph office, so the question of expense cannot 
stand in the way of the substitution of hydraulie limes for those in common 
use. 
At present the annual consumption of Portland cement in New Zealand 
is about 40,000 casks, representing an expenditure to the consumer of 
£40,000. Ofthis quantity I am confident that nine-tenths is used in works 
for which our native products are equally well adapted ; indeed, with the 
exception of some wet tunnel lining and foundations, where quick setting 
was a desid@ratum, there have been few works executed in New Zealand 
that required cement. We are, therefore, spending £36,000 on a foreign 
article, while a native one that would serve our purpose can be obtained at 
half the cost. This state of affairs has resulted entirely from ignorance of 
our resources, and of the quality of the materials within our reach. 
The principal hydraulic limestones of the Peninsula are rather inac- 
cessibly situated; at present their only outlet is by road to Dunedin, a 
distance of ten miles, but a moderate expenditure on a tramway two miles 
long would connect them with the proposed Portobello Railway and the 
waters of the harbour. The deposit at Dowling Bay occupies a very favour- 
able position on the beach, four miles below Port Chalmers. The newroad 
to the Heads passes through it, and there is deep water within a few yards 
of the limestone rock. 
In order to utilise these stores of hydraulic limes to the best advantage, 
I would suggest the adoption of a plan that seems to have been followed in 
America: The quality of the stone, not only in each quarry, but in each 
bed of that quarry, is so clearly determined that its name conveys a distinct 
meaning to professional men who stipulate for certain kinds in certain 
work. Gradually the names acquire a commercial value, like the brands in 
ordinary manufactures, and thus the public generally acquire the know- 
ledge necessary to ensure each article being used in its proper place. 
b 
