STATE GEOLOGIST. Dili 
The specifications in use in Washington, D. C., are as follows: 
4 Concrete Base. —Upon the bed (Ssub-grade) thus prepared there will be 
laid a four (4) or six (6) inch foundation of concrete, as directed, made of 
broken stone and gravel, sand, and natural cement in such proportions that the 
quantity of gravel will be equal to the volume of voids in the broken stone, 
and the sand and cement, mixed in the proportion of one (1) part cement and 
two (2) parts sand, will be 20 per cent. in excess of the volume of voids 
in the combined gravel and broken stone. 
5, Hydraulic Cement. —The cement in use shall be a natural hydraulic 
cement, and shall conform to the current specifications for supplying such 
hydraulic cement to the Engineer Department of the District of Colum- 
bia. No hydraulic cement shall be used upon the work until it has been 
tested in the office of the Engineer Commissioner and accepted by him, the 
tests to extend over such length of time, not exceeding twenty-eight days, 
as the Engineer Commissioner may think necessary. The cement, while in 
storage or upon the work, while being hauled upon the work, shall be 
properly protected, and no cement shall be used which, in the opinion of the 
Engineer Commissioner, has been injured by age or exposure. The cement 
shall be kept by the contractor in store, under proper cover, in the city of 
Washington, and subject to inspection for at least ten days before it is 
used on the streets, and if deemed advisable by the Engineer Commissioner, 
twenty-eight days. Should the contractor’s work be delayed by his failure 
to keep himself supplied with the necessary amount of approved cement, 
the District shall have the right to furnish him with tested cement from the 
stock on hand at its warehouse and charge said contractor with the cost 
of same at the rate of seventy-five (75) cents per barrel for each and every 
barrel so furnished, and collect the amount due therefor from any moneys 
found to be due to said contractor by the District. 
6, Sand,—The sand used shall be clean, sharp river sand, containing 
both fine and coarse grains, but free from sewerage, mud, clay, mica, paper, 
leaves, chips, and other foreign matter, and not showing, when shaken with 
water and after subsidence, more than five (5) per cent., by volume, of silt. 
7. Broken Stone, —Stone used in concrete must be hard, durable, and 
properly broken to a size small enough in their largest dimensions to pass 
through a ring two (2) inches in diameter, and none smaller than 4 inch 
can be used. It shall be thoroughly cleansed from all foreign substance 
and shall be screened and washed, if so ordered by the Engineer. Sand, 
detritus, or any material other than hard, angular fragments of stone will be 
considered foreign substances. 
8. Gravel,—Gravel shall be clean, washed gravel, and shall not contain 
pebbles greater than one and one-half (114) inches in their largest dimensions. 
9, Water.—Water used for mortar and concrete shall be fresh and clean, 
free from earth, dirt, or sewerage, and shall be used in Such quantity as the 
Engineer may direct. 
10.  Platforms,—-Platforms shall be provided upon which all sand, gravel 
and broken stone shall be placed when brought upon the line of the work, 
and kept there until used. 
Ne Mixing.—Concrete may be mixed by hand labor or by machinery, but, 
in either manner, the thorough incorporation of the several materials required 
will be insisted upon. If machinery is employed for the purpose, its operation 
