42 



NATURE 



[March 15, 1917 



(3) Practical Experiments in Light. Pp. viii + 



112. By W. St. B. Griffith and P. T. Petrie. 



(London : Rivingtons, 1916.) Price 35. 6d. 



net. 

 (x) 'T^HE fourth edition of the "Text-book of 

 1 Physics " edited by Prof.. A. Wilmer 

 Duff shows numerous changes, especially in the 

 paragraphs dealing with the dynamics of rotation. 

 A new part on sound has been prepared, in which 

 recent important work is described, including the 

 researches of Prof. Miller by means of his " phono- 

 deik " and the experiments of Prof. Sabine on 

 architectural acoustics. A careful study of the 

 results obtained by the latter investigator has 

 shown that attempts to reduce reverberation by 

 stretching fine wires across a hall or by similar 

 devices are entirely useless. Other sections of this 

 excellent treatise have also been brought up to 

 date ; we notice an interesting account of Dr. 

 Langmuir's mercury-vapour pump, which is given 

 high praise : " Because of its remarkable sim- 

 plicity and rapidity of action, it marks a great 

 advance in methods of obtaining high vacua." 

 The only criticism of the volume we have to make 

 is that some of the illustrations {e.g. the tangent 

 galvanometer, p. 384) are scarcely worthy of the 

 text. 



(2) and (3) The authors of these text-books on 

 practical physics are masters at Uppingham 

 School, and they have found, as have other 

 teachers, that a laboratory guide, either written 

 or printed, is requisite for the efficient teaching 

 of large classes. There are drawbacks to every 

 method of instruction ; some students are met 

 with who, from mental inertia or defective ele- 

 mentary education, seem incapable of following 

 the description of an experiment given in print, 

 whilst they can understand an oral account. 

 Others, again, slavishly follow the printed page, 

 and will even copy the diagram in their text-book 

 instead of sketching the actual apparatus used. 

 In such cases it is, perhaps, unfortunate that all 

 the quantitative experiments should be illustrated 

 by worked-out numerical examples. The books 

 under discussion are intended "for the use of 

 boys between the ages of thirteen and twenty." 

 Their chief recommendation is the large number 

 of simple experiments which can be carried out 

 without the use of elaborate apparatus. Graphical 

 methods are rightly emphasised, and a word of 

 praise must be given to the clearly drawn graphs 

 reproduced in the text. Some of the other 

 diagrams in " Heat " are not quite so satisfactory. 



The directions given are, as a rule, lucid and 

 exact, but occasionally we find a misleading or 

 careless sentence — e.g. "Do not touch the calori- 

 meter and use the thermometer as a stirrer " 

 (p. 50); "The temperature of different Bunsen 

 flames vary considerably " (p. 71). The authors do 

 not appear to realise that convection plays a more 

 important part than radiation in the cooling of a 

 hot body. In the chapter on calorlmetry (one of 

 the best In "Heat") the calorimeter, "bright 

 on the outside," should not be exposed on the 

 NO. 2472, VOL. 99] 



bench, but be supported in an outer metal vessel 

 or be wrapped with cotton-wool and put in a 

 beaker. The account of Newton's law of cooling 

 is defective for the same reason. It is to be 

 regretted that in the experiment on Boyle's law 

 the results are tabulated with six significant 

 figures, though the observations contain only three 

 figures. The authors have not even the excuse 

 of Blot, who, when his attention was drawn to a 

 similar case, replied sarcastically that if the first 

 figures were wrong, perhaps the last would be 

 right. In Regnault's hygrometer the end of the 

 boiling tube must be cut off before the metal 

 thimble is cemented to it. There are In all fifty- 

 nine experiments In " Heat " and sixty-eight in 

 "Light." The experiments In "Light" are of 

 the type now familiar, pin methods being employed 

 frequently. In the first experiment, which pur- 

 ports to show that light travels in straight lines, 

 It is necessary to prove that the hat-pin (used to 

 test the alignment of the holes In the three card- 

 board screens) is straight. As an optical method 

 is Inadmissible, this might be done by fixing two 

 of the screens, rotating the hat-pin, and noticing 

 whether there is any lateral displacement of the 

 third screen. The questions addressed to the 

 student form a valuable feature in connection with 

 the earlier part of the Light course. H, S. A. 



THE TECHNOLOGY OF TYPOGRAPHICAL 

 PRINTING SURFACES. 



Typographical Printing-surfaces: the Technology 

 and Mechanism of their Production. By L. A. 

 Legros and J. C. Grant. Pp. xxiv + 732. 

 (London: Longmans, Green and Co., 1916.) 

 Price 2I. 25. net. 



THIS work is the outcome of a paper read by 

 one of the authors Before the Institution of 

 Mechanical Engineers a few years ago : the paper 

 created at the time some amount of interest in 

 the printing world owing to the thoroughness 

 with which it had been prepared. That matter 

 has now been considerably enlarged — perhaps too 

 much so in some instances — but we must readily 

 admit the usefulness of the bulk of the Information 

 collected together, because of its previously being 

 scattered abroad in many directions, and due 

 credit must be given to the compilers for the great 

 labour involved In bringing together so much 

 valuable material ; certainly as a work of re- 

 ference on Its subject the book will be found 

 most useful. 



The volume Is jointly dedicated to our first 

 authority on printing, Joseph Moxon, 1627-1700, 

 and to the French writer, Simon Fourrier, another 

 great authority, 1712—68, and is a stupendous 

 work of its kind. As It professes, it covers a 

 good deal of the ground which hitherto has been 

 but scantily treated, so far as type-founding] 

 Is concerned, in any English text-book on print- 

 ing ever published. In fact, Moxon, in his 

 "Mechanick Exercises," 1683, Is the only writer 



