As the number of samples is dependent
upon the footage of openings on the deposit, a rough approximation
can be made in advance, and a general idea obtained as to the time
required. This period must be insisted upon.

REPORTS.

Reports are to be read by the layman, and their first qualities
should be simplicity of terms and definiteness of conclusions.
Reports are usually too long, rather than too short. The essential
facts governing the value of a mine can be expressed on one sheet
of paper. It is always desirable, however, that the groundwork data
and the manner of their determination should be set out with such
detail that any other engineer could come to the same conclusion
if he accepted the facts as accurately determined. In regard to the
detailed form of reports, the writer's own preference is for a single
page summarizing the main factors, and an assay plan, reduced to a
longitudinal section where possible. Then there should be added,
for purposes of record and for submission to other engineers, a
set of appendices going into some details as to the history of
the mine, its geology, development, equipment, metallurgy, and
management. A list of samples should be given with their location,
and the tonnages and values of each separate block. A presentation
should be made of the probabilities of extension in depth, together
with recommendations for working the mine.

GENERAL SUMMARY.

The bed-rock value which attaches to a mine is the profit to be
won from proved ore and in which the price of metal is calculated
at some figure between "basic" and "normal." This we may call the
"_A_" value. Beyond this there is the speculative value of the
mine. If the value of the "probable" ore be represented by _X_,
the value of extension of the ore by _Y_, and a higher price for
metal than the price above assumed represented by _Z_, then if
the mine be efficiently managed the value of the mine is _A_ +
_X_ + _Y_ + _Z_. What actual amounts should be attached to _X,
Y, Z_ is a matter of judgment. There is no prescription for good
judgment. Good judgment rests upon a proper balancing of evidence.
The amount of risk in _X, Y, Z_ is purely a question of how much
these factors are required to represent in money,--in effect, how
much more ore must be found, or how many feet the ore must extend
in depth; or in convertible terms, what life in years the mine
must have, or how high the price of metal must be. In forming an
opinion whe