March 5, 1896] 



NATURE 



411 



" A man who deserves of his country and of literature 

 the highest praise, not only for his numerous important 

 writings on the relations of physicians, on the proper 

 construction and administration of hospitals, on the 

 public health of the United States according to the 

 precepts of the science and art of hygiene, on the pre- 

 servation and improvement of the health of the army, 

 but also for the great collections thereto relating which 

 he has established and extended ; a man who, in the 

 " Index Medicus'' of which he is the editor, includes by 

 indefatigable industry all the branches of medicine that 

 are being advanced throughout the whole world, who 

 also, as author of the book entitled the " Index-Catalogue," 

 which by the remarkable munificence of the Government 

 of the United States has been laid before an immense 

 number of learned men, has entitled himself to the 

 gratitude of physicians and students of history over the 

 entire world, and has fashioned for himself a monument 

 more enduring than brass." 



It must be remembered that not only the "Catalogue" 

 but the Library itself is essentially of Dr. Billings' creation, 

 and that about one-sixth of its contents have been pre- 

 sented either by way of direct gift or in exchange. It 

 speaks highly for his personal " magnetism " that he can 

 write : " There are few medical writers now living who 

 have not sent to the Library at least one pamphlet." 

 Thus, while the " Catalogue " has been passing through 

 the press, a multitude of fresh gifts and additions have 

 accumulated, and the completion of the " first series " 

 only makes way for the commencement of a second. 

 The manuscript of this is already prepared, and will be 

 forthwith printed in five volumes as large and full as 

 those already given to the world. Dr. Billings has taken 

 up new duties in a different sphere of activity ; but the 

 " labour of love " which he here dedicates to international 

 science will still be carried on under the inspiration of 

 his singular genius. The gratitude of his innumerable 

 debtors will be enhanced by a lively expectation of 

 benefits to come. 



OUR BOOK SHELF. 

 Mestires Electriques. By Eric Gerard. (Paris : Gauthier- 



\'illars et P'ils, 1896.) 

 To those who are acquainted with M. Gerard's previous 

 work (" Lemons sur I'Electricite"), the publication of the 

 jjiesent work will probably be extremely welcome, for in 

 it he has, in his usual clear and satisfactory style, gone 

 more fully into the question of the measurement of 

 electrical quantities. 



In an introductory chapter, the author considers the 

 ([uestion of the errors of observation, and the effects they 

 have on the final result. In this discussion, that 

 interesting branch of pure mathematics called the method 

 of least squares for determining the probable error, and 

 which, in the hands of many observers, seems to perform 

 much the same function as the ink does in the case of the 

 cuttle-fish, is left comparatively in the background. Such 

 questions as errors of observation — properly so called — 

 and of systematic errors are, however, dealt with, and the 

 importance of exercising judgment in deciding the 

 accuracy with which the different quantities have to be 

 observed, in order that the result may be correct to 

 within a certain amount, is insisted upon. There is one 

 paragraph which ought to be written up as a text in all 

 laboratories and testing-rooms, and is to the effect that 

 in making electrical connections too much care cannot 

 be taken in arranging the wires and in cleaning the 



NO. 1375, VOL. 53] 



contacts, and that connecting wires ought not to consist 

 of long spirals, for these only serve to increase the 

 resistance and self-induction of the circuit. Some very 

 useful instructions as to the best method of recording 

 observations are given, together with some hints as to 

 choice of an algebraic function to represent a given 

 curve. 



There is also a chapter on the measurement of lengths, 

 time, angles, forces, velocity and power ; and one on photo- 

 metry, a subject which, since the expiration of the 

 incandescent lamp patent, and the introduction of the 

 incandescent gas-lamp, has become of very great 

 importance to the electrician. 



The more purely electrical part of the book consists of 

 chapters on electrical standards, galvanometers (including 

 ammeters), voltmeters, coulomb- and watt-meters, and two 

 very fairly complete chapters on the measurement of 

 self-induction, and the magnetic properties of iron. 

 There are also chapters on the measurements of the 

 characteristics of motors and dynamos (both for con- 

 tinuous and alternating currents), and on transformers. 

 Although the devotee to the slide-rule is probably bom 

 and not made, an appendix on this instrument may be of 

 service to those who have not yet been initiated. 



The whole book is essentially a practical and readable 

 text-book, though, perhaps, hardly a laboratory manual 

 of the subject ; it is remarkably free from useless and 

 uncalled-for mathematical formula;, and will undoubtedly 

 be found of great use. W. W. 



Problems in the Use and Adjustment of Engineering 

 Instruments. By Walter Loring Webb, C.E. (Pp. 

 iv -I-64. fNewYork : John Wiley and Sons. London : 

 Chapman and Hall, Ltd., 1895.) 



Ix every college or university where field work is a 

 subject in the curriculum, such a book as this is found to 

 be almost indispensable. Its aim is to set out problems 

 for each student or group of students to pursue, in order 

 that no time shall be lost, and so that every one may 

 have complete practice with individual instruments. For 

 such a purpose, this is perhaps one of the most concisely 

 written books on the subject, and it at the same time 

 covers a large amount of ground, from single chain 

 measurement to a preliminary railroad survey. 



Besides the instruments usually noted, one is glad to 

 see instruction with the plane table and Amsley's polar 

 planimeter, both such very admirable instruments when 

 used with precision, that it is remarkable their introduction 

 is not more universal. Throughout the book, convenient 

 forms for entering notes are shown, and there is also a 

 short chapter on the use of the formulae of probable 

 error, the utility of which cannot be over-estimated. 



Graphic Arithmetic. By H. D. Ellis. (Philip and 



Son, 1896.) 

 This contribution to the teaching of arithmetic consists 

 of two charts, each 40 in. by 10 in., which can be mounted, 

 or otherwise adapted to class teaching. Chart i., whole 

 numbers, consists of a series of horizontal lines, divided 

 by dots respectively into ones, twos, threes, &c., twelves. 

 By means of vertical lines the multiples of 2, 3, &c., are 

 shown on the line of ones, which is numbered from o to 

 144. In Chart ii., fractions (vulgar and decimal), the series 

 of horizontal lines are i metre in length and i cm. apart. 

 These lines are divided by dots into halves, thirds, &c., 

 tenths. There are subdivisions into hundredths (cm.) and 

 thousandths (millim). On Chart i. explanations are given 

 of magnitude, unit, number, multiple, «Si:c. ; and on ii., of 

 the multiplication and division of decimals, the expression 

 of a vulgar fraction as a decimal, and several other 

 matters. The charts are well adapted for the purpose 

 of giving a sound grounding in the subject, so fur as 

 they go. 



