One reason of this general ignorance has been the absence of any text-book or manual on the subject, giving a clear and thorough exposition of its mysteries.  The present is the first American work which takes the subject in hand from the beginning and carries it through the entire process which leads to the results we have spoken of.  Its author brings to his work the best possible qualification,—­a long familiarity with the subject in the every-day details of its development.  His Introduction informs the reader that he has been engaged for thirteen years in the business of practical telegraphing.  He is thus sure of his ground, from the best of sources, personal experience.

We shall not criticize the work in detail, but shall rest satisfied with saying that the author has succeeded in his design of making the whole subject clear to any reader who will follow his lucid and systematic exposition.  The plan of the work is simple, and the arrangement orderly and proper.  A concise statement is given of the fundamental principles of electricity, and of the means of its artificial propagation.  This includes, of course, a description of the various batteries used in telegraphing.  Then follows a chapter upon electro-magnetism and its application to the telegraph.  This prepares the way for a statement of the physical conditions under which the electrical current may be conveyed.  The author then describes the instruments necessary for the transmission and recording of intelligible signs, under which general head of “Electric Telegraph Apparatus” the various telegraphic systems are made the subject of careful description.  A chapter is given to the history of each system,—­the Morse, the Needle, the House, the Bain, the Hughes, the Combination, and others of less note.  These chapters are very complete and very interesting, embodying, as they do, the history of each instrument, the details of its use, and a statement of its capabilities.  The system most used in America is the Combination system, the printing instrument of which is the result of an ingenious combination of the most desirable qualities of the House and Hughes systems.  Of this fine instrument a full-page engraving is given, which, with Mr. Prescott’s careful explanation, renders the recording process very clear.

The next division of the work relates to subterranean and submarine telegraphic lines.  Of this the greater portion is devoted to the Atlantic cable, the great success and the great failure of our time.  The chapter devoted to this unfortunate enterprise gives the completest account of its rise, progress, and decline that we have ever seen.  It seems to set at rest, so far as evidence can do it, the mooted question whether any message ever did really pass through the submerged cable,—­a point upon which there are many unbelievers, even at the present day.  We think these unbelievers would do well to read the account before us.  Mr. Prescott informs us, that, from the first laying of the cable to the