PREFACE TO THE SECOND EDITION IN this Edition there has been added miscellaneous matter in the Addenda relating to the following subjects Crater Forms and the Influence of Flexure thereon Prof. Hofers Theory of Blasting and Military Mining Relation of Explosive Force to Resistance of Rock The Best or Most Economical Length of Borehole Charge Safety Explosives and a Special Article to demonstrate the wrong premises on which Prof. Hofers Theory of Blasting is based. It is a remarkable fact that the theories of rock blasting which have been generally adopted, do not take into account the influence of the form of the chamber employed, seeing that the initial force of the blast, and the resistance of the rock will largely depend thereon for any direction of the line of resistance. The methods by which the rules and formula were deduced are fully explained, and examples of all the more important calculations are given to assist the engineer to deal with any question that may arise in...