im endeavor to find to whom the origin
of our methods should be credited. The science has grown by small
contributions of experience since, or before, those unnamed Egyptian
engineers, whose works prove their knowledge of many fundamentals
of mine engineering six thousand eight hundred years ago. If I
have contributed one sentence to the accumulated knowledge of a
thousand generations of engineers, or have thrown one new ray of
light on the work, I shall have done my share.

I therefore must acknowledge my obligations to all those who have
gone before, to all that has been written that I have read, to
those engineers with whom I have been associated for many years,
and in particular to many friends for kindly reply to inquiry upon
points herein discussed.

CONTENTS.

CHAPTER 1.

Valuation of Copper, Gold, Lead, Silver, Tin, and Zinc Lode Mines

Determination of average metal content; sampling, assay plans,
calculations of averages, percentage of errors in estimate from
sampling.

CHAPTER II.

Mine Valuation (_Continued_)

Calculation of quantities of ore, and classification of ore in sight.

CHAPTER III.

Mine Valuation (_Continued_)

Prospective value. Extension in depth; origin and structural character
of the deposit; secondary enrichment; development in neighboring
mines; depth of exhaustion.

CHAPTER IV.

Mine Valuation (_Continued_)

Recoverable percentage of the gross assay value; price of metals;
cost of production.

CHAPTER V.

Mine Valuation (_Continued_)

Redemption or amortization of capital and interest.

CHAPTER VI.

Mine Valuation (_Concluded_)

Valuation of mines with little or no ore in sight; valuations on
second-hand data; general conduct of examinations; reports.

CHAPTER VII.

Development of Mines

Entry to the mine; tunnels; vertical, inclined, and combined shafts;
location and number of shafts.

CHAPTER VIII.

Development of Mines (_Continued_)

Shape and size of shafts; speed of sinking; tunnels.

CHAPTER IX.

Development of Mines (_Concluded_)

Subsidiary development: stations; crosscuts; levels; interval between
levels; protection of levels; winzes and rises. Development in the
prospecting stage; drilling.

CHAPTER X.

Stoping

Methods of ore-breaking; underhand stopes; overhand stopes; combined
stope. Valuing ore in course of breaking.

CHAPTER XI.

Methods of Supporting Excavation

Timbering; filling with waste; filling with broken or