value as to the place whence the shock emanated, how deep this was under the earth, or in what direction it emerged from beneath it.
As this method of seismic observation then, is novel, as I trust to show that it has proved fruitful in result, in this its very first application to nature; and as, when fully developed, it will be found a real "Organon," a powerful machine for future discovery, I make no scruple in treating at considerable length of its methods, in the hope that they may become understood, diffused, and applied by others. This method, I believe, will be hereafter recognized as one of the most fruitful applications yet made of mathematics to physical geology.
Before leaving England for Naples, I communicated my views as to this method of investigation to my friend the Rev. Samuel Haughton, F.R.S., Professor of Geology, Trinity College, Dublin, and requested him to arrange for me a series of workable equations that should embrace most of the conditions as to direction and velocity of fractured or overthrown bodies that I expected to meet. With the utmost readiness, he applied his adroit and eminently practical mathematical powers to the task, and from him I received the equations given at pp.&160;125 et seq.—I. to XLV.—which formed some of the most valued working tools of my deductions.
