It will no doubt occur to some who may care to examine with the requisite attention what has been said on comparative costs, to take exception to some of my conclusions. Such friendly critics will no doubt remember the differences which are to be found in the experience of individual mining and manufacturing establishments. My object at the time of my enquiries was one of a purely private nature made without any intention of future publication. They were undertaken for my own guidance, and the opinions I have formed, correct or otherwise, are faithfully recorded in the pages of the present work.
It will be readily understood how largely I am indebted to my fellow workers in the great field of industrial enterprise which I have attempted to explore, for information respecting their practice and experience. I only regret that the confidential character of of the communications I have received, prevents many my cordially thanking, by name, those who have so materially assisted me in the course of my investigations. Other sources of information will be found acknowledged in the proper places.
Under ordinary circumstances I might have dispensed with any allusion to the aid rendered by experimental research; but this, in my own case, has been done in so careful and conscientious a way by Mr. Rocholl in the Clarence laboratory, that I cannot refrain from acknowledging his zeal in this respect, as well as recognizing the thought he bestowed on the examination of the numerous calculations rendered necessary by the nature of the subject.