238 Examination of Mines. 
number of cubic feet of ore in block A. In like manner 
determine the cubical contents of all other sections of 
which three sides have been sampled and measured, as 
B, D, and H. The two sides respectively of the triangu- 
lar figures C, E, G and the portion m h, are next sam- 
pled, measured, and the cubical contents of each trian- 
gular mass determined as above. 
Having the sum of the several ore masses in terms 
of cubic feet, to calculate the number of tons (of 2,000 
pounds) of ore in sight. Rule: Divide the total num- 
ber of cubic feet in the deposit by 32, and multiply the 
quotient by the specific gravity of the ore; the product 
equals the tonnage sought. . 
In practice it is customary to estimate the ore of 
which only two sides have been sampled separately from 
that of which three sides were shown. When sampling 
a mining property it should be borne in mind that the 
richer ore generally lies in chutes. These chutes are dia- 
gramed out and their tonnage estimated independent of 
the poor ground or intervening low grade ores. In any 
event, the method of sampling and computation adapted 
should be fully explained in the report. 
Note.—The more general rule among engineers and 
mine operators is that three sides, at “least,” of the ore 
body shall be sampled before an estimate of ore in sight 
can be made. 
SURVEY AND MAPS. 
If reliable maps and drawings of the mine are not 
at hand, about the first thing to do is to make a survey 
of both surface and underground workings and from 
this survey prepare a map of the claims, a plan of the 
mines and at least two sections of the workings. On 
these drawings in both plan and sections should appear 
the numbers and position of all samples taken. 
