Chapter I: Preface

During the past decade, numerous and great changes have taken place in the system followed and the methods adopted for blasting rocks in industrial operations. The introduction of the machine drill led naturally to these important changes. The system which was suitable to the operations carried on by hand was inefficient under the requirements of machine labour, and the methods which had been adopted as the most appropriate in the former case were found to be more or less unsuitable in the latter. Moreover, the conditions involved in machine boring are such as render necessary stronger explosive agents than the common gunpowder hitherto in use, and a more expeditious and effective means of firing them than that afforded by the ordinary fuse. These stronger agents have been found in the nitro-cotton and the nitro-glycerine compounds, and in the ordinary black powder improved in constitution and fired by detonation; and this more expeditious and effective means of firing has been discovered in the convenient application of electricity. Hence it is that the changes mentioned have been brought about, and hence, also, has arisen a need for a work like the present, in which the subjects are treated of in detail under the new aspects due to the altered conditions.

GEO. G. ANDRÉ.

LONDON, 17, KING WILLIAM STREET, STRAND,

_January 1st, 1878._

CONTENTS.

CHAPTER I.
THE TOOLS, MACHINES, AND OTHER APPLIANCES USED IN ROCK BLASTING.

PAGE
Section I. _Hand-boring Tools._--Drills. Hammers. Auxiliary
Tools. Sets of Blasting Gear 1

Section II. _Machine-boring Tools._--Machine Rock-drills. Borer-
bits. Drill Carriages 23

Section III. _Appliances for firing Blasting Charges._--Squibs.
Safety Fuse. Electric Fuses. Cables. Detonators. Electric Firing-
Machines 42

CHAPTER II.
EXPLOSIVE AGENTS USED IN ROCK BLASTING.

Section I. _Phenomena accompanying an Explosion._--Nature of an
Explosion. Heat liberated by an Explosion. Gases generated by an
Explosion. Force developed by an Explosion 64

Section II. _Nature of Explosive Agents._--Mechanical Mixtures.
Chemical Compounds 76

Section III. _Relative Strength of the common Explosive Agents._--
Force developed by Gunpowder. Relative Force developed by
Gunpowder, Gun-cotton, and Nitro-Glycerine 88

Section IV. _Means of firing the common Explosive Agents._--Action
of Heat. Detonation 92

Section V. _Some Properties of the common Explosive Agents._--
Gunpowder, Gun-cotton, Dynamite. Firing Temperatures 97

Section VI. _Some Varieties of the Nitro-Cellulose and the Nitro-
Glycerine Compounds._--Nitrated Gun-cotton. Tonite, or Cotton-
Powder. Schultze’s Powder. Lithofracteur. Brain’s Powder.
Cellulose-Dynamite 103

CHAPTER III.
THE PRINCIPLES OF ROCK BLASTING.

Line of least Resistance. Force required to cause Disruption.
Conditions of Disruption. Example of a Heading. Economical
Considerations. Tamping 106

CHAPTER IV.
THE OPERATIONS OF ROCK BLASTING.

_Hand Boring._--Boring the Shot-holes. Charging the Shot-holes.
Firing the Charges 128

_Machine Boring._--Boring the Shot-holes. Charging and Firing.
Removing the dislodged Rock. Division of Labour 142

_Examples of Drivings._--The St. Gothard Tunnel. The Hoosac
Tunnel. The Musconetcong Tunnel. Headings at Marihaye, Anzin, and
Ronchamp 157