178 



SCIENCE. 



[Vol. XV. No. 371 



bacillus was still capable of producing a local tubercular 

 abscess, not followed by general infection. Over twelve hours' 

 digestion destroyed it completely. The germicide influence of 

 gastric juice appears to be due to its acid contents, as it was 

 found that hydrochloric acid alone, dissolved in water in the 

 same proportion as it is in gastric juice, proved as active a 

 destroyer of the bacilli. The pepsin appears to have no inilu- 

 ence on the germs. Drs. Straus and Wurtz, who publish their 

 researches in Archives de Medecine Experimentale , wisely 

 remind their readers that the germs, when protected by 

 animal and vegetable tissues and introduced into the stomach 

 in ordinary nutrition, are not exposed to so direct and pro- 

 longed action of the acid constituents of gastric juice as in 

 these experiments. 



BOOK-REVIEWS. 



Electric Light Installations and the Management of Accumula- 

 tors. By Sir David Salomons. New York, Van Nostrand. 

 13°. $1.50. 



As this is the fifth edition of a work which first appeared 

 only two or three years ago, it is unnecessary to say that it 

 fills a very important place in the literature of electrical 

 science. It is not intended as a text-book on electric lighting, 

 nor is it addressed to electricians as such ; but it covers a field 

 of its own, which had been previously neglected, or, rather, a 

 field which had not been as alluring to writers on the subject 

 as had other departments of the science. 



Though the author disclaims any pretence to literary style, 

 his work proves that he possesses in a high degree the three 

 essential requisites of a successful writer; namely, to have 

 something interesting to say, to be able to say it so that it 

 may not be misunderstood, and to stop when he has said it. 

 As a result, he has given us a plain statement of facts in 

 regard to the practical side of electric lighting and the manage- 

 ment of accumulators, attractively and clearly presented, and 

 in as concise a manner as is consistent with the nature of the 

 subject. The author proceeds on the assumption that the 

 reader has a general knowledge of electric lighting, omitting 

 minor details, which may best be found in any elementary 

 book on the applications of electricity. 



To those familiar with the work in its previous editions, it 

 may be well to mention that this edition has been carefully 

 revised and greatly enlarged, besides which many new engrav- 

 ings have been introduced, rendering the text more intelligible 

 and at the same time showing the various types of electrical 

 apparatus adopted by different manufacturers. To those who 

 have never read the book, its scope may best be gathered from 

 the author's statement that previous to its appearance no book 

 had been written on the special subject of the management of 

 the accumulator. Of the two classes of persons most directly 

 interested in the secondary battery, manufacturers and pur- 

 chasers, the former, as a rule, know comparatively little of its 

 properties, their knowledge being confined mainly to laboratory 

 tests. The true knowledge of how a battery will act is gained 

 only by long experience. "While it is in the hands of a non- 

 professional user, rarely competent to examine the question for 

 himself, this knowledge cannot be gained or turned to account. 

 There are but few who have both the opportunity and the quali- 

 fications necessary to observe, scientifically as well as prac- 

 tically, the working of an accumulator, and fewer still with 

 time, opportunity, and inclination to write upon the subject. 

 To fill this gap, between the manufacturer and the general 

 user, the author has attempted ; and the demand for the present 

 work proves that his attempt has met with a full measure of 

 success. 



The book is divided into two parts, the first treating of cells 

 and their mode of employment ; the accumulator house ; char- 

 ging and discharging; and failures, with their causes and 

 remedies. The second part is devoted to installation work and 

 practice, treating of engines, dynamos, and motors; switch- 

 boards, switches, instruments, lamps, and wiring; rules for 

 the prevention of fire risks; action of cells with dynamo; 



methods of working and governing; alternating currents, 

 testing, and estimating, etc. ; ending with a description and: 

 history of the author's own private installation of secondary 

 batteries at Broomhill. The book is fully illustrated, and: 

 provided with a very complete index. 



A Text-Book on Roofs and Bridges. Part II. Graphic Statics. 

 By Mansfield Meeriman and Heney S. Jacoby. New 

 York, Wiley. 8°. |3.50. 



This volume, as its name indicates, is a treatise on graphic 

 statics as applied to the discussion of common roofs and 

 bridges. It is an outgrowth of the course of instruction in 

 the subjects named, given to the students of civil engineering 

 in Lehigh University, in which institution the authors are- 

 respectively professor of and instructor in that branch of 

 applied science. The course in civil engineering in the 

 university mentioned consists of four parts; namely, the com- 

 putation of stresses in roof-trusses and in all the common 

 styles of simple bridge-trusses; the analysis of stresses by 

 graphic methods ; the design of a bridge, including the propor- 

 tioning of details and the preparation of working drawings; 

 and the discussion of cantilever, suspension, continuous, and 

 arched bridges. In this volume the second part of this course 

 is presented, together with much additional matter. 



Being offered as an elementary text-book, we need not look 

 for many novelties in the work aside from the method of 

 arrangement and presentation, though we may call attention 

 to the abbreviated processes employed in some of the diagrams 

 for wind-stresses, to the determination of stresses due to initial 

 tension, and to portions of the analysis of maximum moments 

 and shearing strains under locomotive wheel loads, as possess- 

 ing some points of novelty as well as of practical value. 



For the convenience of students, blank leaves are provided, 

 alternating with the printed pages, upon which to record the 

 numerical computations necessary in the preparation of 

 graphical analyses, and upon which to make sketches of the- 

 stress diagrams required in the problems. The book is divided 

 into three main parts, treating respectively of general prin- 

 ciples and methods, of roof ■ trusses, and of bridge-trusses. 

 An appendix contains the answers to the problems. The- 

 work is written in a clear and attractive style, and, though 

 intended mainly as a text-book for students, it is not without 

 value to engineers and others. 



Elements of Logic as a Science of Propositions. By E. E. Con- 

 stance Jones. Edinburgh, T. & T. Clark. 8°. $3. 



This book is a very ambitious, but, as it seems to us, very 

 unsuccessful, attempt to reconstruct the science of logic. The 

 author takes the ground that logic is an objective science, and 

 not a branch of psychology, and then goes on to define it as. 

 "the science of the import and relations of propositions," 

 denying altogether that it is a science of reasoning or of the 

 laws of thought. The chief characteristic of the treatise, how- 

 ever, is not the view taken of the science, nor any new or 

 startling theory of its fundamental principles, but the employ- 

 ment of an immense number of new-fangled terms in place of 

 the familiar ones that have been in use for centuries. What 

 the object of such an innovation may be, unless to give the 

 work an air of originality, we do not know ; for we fail to see 

 in what respect the new nomenclature is an improvement on 

 the old. Thus, we cannot see the propriety of calling exist- 

 ence ' 'quantitiveness, ' ' nor of using the phrase ' 'subject of 

 attributes" instead of the familiar term "substance." Essen- 

 tial attributes are termed by the author "intrinsic," and acci- 

 dental ones ' 'extrinsic : " an absolute attribute is called 

 "independent," and a relative one "dependent;" hypothetical 

 propositions are "inferential," and disjunctive ones "alter- 

 native;" and so on throughout the book, till the reader who 

 looked at the terminology only might almost fancy that he 

 was studying a new science. Yet, apart from this strange 

 terminology, we fail to find in the work any thing specially 

 new or noteworthy, while in some passages there is evidence of 

 much confusion of thought. This is specially apparent in. 



