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of any stone that shows the least,
sign of discoloration or disintegration - The best and largest blocks should be picked out and set avide for the lower portions of the structure and the generality of the
stones used should not average less than three feet cube .
19 Mortar - The question of the compoortion of the
20
Mortar to be used in the rubble work has received my
careful consideration... As the point is one
that very materially affects the estimate of the cost of the dam. I would have been dispoved to acquiesce the ground of economy
more Ao
on
our.
in the adoption of a mortar mod from the lime obtained locally had I satisfactory assurances that the Hong Kong limes thoroughly hydraulic as the best of English hydraulic lines, but Mr. Pruce buing of Aurion that the best Hong Kong limes fall short; the standard of excellence that would be required for this Country Jam disposed
similar works in this
le advise as a matter of prudence, that notwith- standing the increased cost (£$500) English Portland Coment should be used throughoudt for the Mortar The composition of the latter, may be 1 part cement to 4 parts clean sharp sand.
The cement should be subjected to careful, tests in this Country before shipment and on reaching the work
• should be a pecord time tested before use. __ It should not- be sent out to the Colony
one or two large cargoes but the supply should be spread ovenly and a half years in small periodical consignments of freshly burnt material each time __
over her
21 Qutlet Works. It is proposed to place the valve
well, and outlet culvert in the heart of the dam._