��THE POPULAR SCIENCE MONTHLY.
��which experience has shown are essential to safety. It is, of course, operated under the block system, without which the operation of any great railroad with its multifarious traffic can not be safe. To listen to the ex- cuses often made by railroad officials for not adopting this system, one would get the idea that it is in some way complex and intricate and not easy of application to railway oper- ation under all circumstances. It is, how- ever, simplicity itself. It does not consist in any necessary forms of appliance, but is sim- ply a method of operating. Mr. Findlay de- scribes some simple forms of indicators used on the London and Northwestern, but any form of indicator may be used. The block system consists simply in dividing a road into a number of sections and allowing but one train at a time in either direction in any given section. To apply it to a road re- quires only the erection of proper signals and suitable means for operating them, and knowing their condition by the operators sta- tioned along the line at the entrance of every block division. It is a matter of no small wonder that the officials of any considerable road should resist the introduction of so sim- ple a method of insuring safety, and that any community should tolerate a railway service not operated in such a manner. The book is very readably written, and can be read with interest by the general public who have to make use of the railways, and with profit by not a few of our railway mana- gers.
Diseases of the Urinary Apparatus. By J. W. S. Gouley, M. D. New York : D. Appleton & Co. Pp. xiii + 342. Price, $1.50.
Criticism of the substance of this trea- tise must be left to that very small minority of the medical profession who are familiar with the latest contributions, made in Europe and in this country, to the author's special branch of their science. It is enough to say on this subject that Dr. Gouley has here brought into one small volume everything which the well-educated practitioner, who is not yet a specialist, needs, to set him on a level with the foremost specialist in urinary surgery and medication except experience. The physician of a scientific habit of inquiry will find it a most stimulating book ; full, in-
��deed, of the facts of observation and prac- tice, but with each fact set forth, not as an isolated fragment of knowledge, but as an essential part of an organic system of truth. At the same time the spirit of inquiry per- vades the whole. The student of the subject is taken into partnership with the teacher in the great work of advancing the boundaries of knowledge. The dogmatism which claims finality and universality for its own formulas is excluded ; and every acquisition is made a stepping-stone in the way to new discovery. One hardly knows, in ending the perusal of these pages, whether the writer is most to be congratulated as the representative of the generation of reformers, who have recon- structed this important branch of medical science and placed it on a lasting basis, or as the harbinger of their successors, who will surely, by following out the same meth- ods to far greater results, add immeasurably to its power to serve mankind.
It is rather our province to speak of the literary form of the work, which certainly deserves special notice. Technical treatises, in every line of professional learning, are so often marked by everything that is forbid- ding in style that it is a rare privilege to meet with one which can be treated as litera- ture. Of course, no such work is designed for popular reading; and this one, in par- ticular, is addressed only to students of spe- cial education and high intelligence. But its special merit is that it is perfectly adapted to its end. There is no waste of words, no tedious repetition, no looseness of statement) no parade of impertinent learning, no obtru- sion of personality. Concise in style, precise in definition, clear in reasoning, orderly and progressive in arrangement, and with an ac- curacy and care in terminology almost with- out precedent, it leads on from the elements of the subject to the very border lines of contemporary knowledge in a steady march, which offers a model in plan to all who would teach subjects of difficulty. We trust that it will receive from the profession a welcome which will be an object-lesson to many medical writers ; for it would be easy to name many whose books, while containing information of great value, would be doubled in usefulness, though halved in size, if re- written after the fashion of this admirable tnulium in parvo.