5 So 



NA TURE 



{April 22, 1886 



Space might have been saved by the exclusion of 

 special subjects, e.}(. lighthouse apparatus, &c., which 

 could not be treated at adequate length. 



A short glossary of uncommon terms would have been 

 decidedly useful, e.g. alveus, bollard, kant, pawl, scend, 

 staith. 



These blemishes are, however, small compared with 

 the great merit of the work as a w^hole, which deals with 

 the difficult and important subject of harbours in a 

 thoroughly masterly manner. 



At.L.\N CuNNiNGHASr, (Major, R.E.) 



OUR BOOK SHELF 

 A First Course of Physical Laboratory Practice. By 

 A. M. Worthington, M.A., late Assistant Master at 

 Clifton College. (London : Rivingtons, 1886.) 

 PR0B.4BLY no one has so successfully carried on practical 

 science teaching in schools as the author whose e.vcellent 

 work at Clifton College has done so much to gain for that 

 institution an enviable reputation. He therefore is 

 specially fitted to write a " First Course of Physical 

 Laboratory Practice " which shall contain just that which 

 the schoolmaster who is endeavouring to supplement 

 mere lectures with the necessary practical work requires. 



In the introduction the author explains the system of 

 science teaching at Clifton. He insists on the importance 

 of from the first making boys themselves measure and 

 experimentally confirm geometrical, mechanical, and 

 physical laws', not necessarily with expensive and ela- 

 borate apparatus, such as may be best suited for making 

 determinations of the greatest accuracy, but by the most 

 simple and obvious methods, which are likely to lead to 

 results quite accurate enough to show the truth of the 

 law being examined. The pupil is thus from the first 

 taught to learn the value of simple and often extem- 

 porised apparatus, instead of acquiring the very general 

 distrust in anything that has not been highly finished by 

 the professional instrument maker. 



Here much that is of great value to those intending to 

 introduce practical science teaching into schools will be 

 found, such as descriptions of fittings, original and working 

 cost, and the time that the several courses of instruc- 

 tion should occupy. 



The book is clivided into nine parts as follows: — 

 I, Mensuration, 23 experiments; 2, Hydrostatics, 15 ex- 

 periments ; 3, Barometer and Boyle's Law, 3 experiments ; 

 4, Mechanics, 39 experiments ; 5, Elasticity, 20 experi- 

 ments ; 6, Heat, 42 experiments ; 7, Magnetism, 55 ex- 

 periments ; 8, Statical Electricity, 57 experiments ; 9, 

 Current Electricity, 16 experiments. The two branches 

 of physics, light and sound, are not included. 



The first part is especially valuable as an introduction to 

 laboratory practice of any kind. It is full of examples 

 in which a good way of observation is contrasted with 

 one or more bad ways, so that the pupil soon learns, or 

 ought to learn, method in observation, to choose that way 

 in which error of observation shall least affect the result. 

 If it is possible to point out any parts as being more 

 excellent than the rest, the chapters on mechanics and 

 elasticity may be mentioned. It is shown how, by means 

 of one or two boxwood scales, a few weights, some pieces 

 of catapult india-rubber (but for sufficient reasons it is 

 not called catapult india-rubber), and some other equally 

 simple and easily obtained articles, a course of experi- 

 ments of the utmost value can be performed. A pupil 

 must, if he gives his mind to the subject, learn more of 

 the principles of mechanics, of the reasons of things— 

 not the mere "pulley, wedge, and lever" mechanics of 

 the ordinary text-books — than as yet the majority of 

 people have ever acquired. 



There is only one sentence which might with advan- 



tage be modified as being not strictly correct, though any 

 false impression which it would produce might be re- 

 moved by the more exact statements five pages later. 

 Having shown that the bending of a lath depends on its 

 length, the author proceeds to show that thickness aftects 

 the bending. He says : — " Now take a lath of double the 

 thickness, or, what is the same thing, lay on the first lath 

 a second similar one, and put on the same weight, ..." 

 This would be a serious blunder to make if the effect of 

 depth were not well shown later. As the fact that the 

 stiffness of a beam is directly proportional to its width is 

 explained by considering it as equivalent to beams side 

 by side, the opportunity is lost, when the effect of depth 

 is considered, of showing that a beam is not equivalent 

 to beams lying above one another, and why. 



As a text-book for school use, Worthington's " First 

 Course of Physical Laboratory Practice" is highly to be 

 recommended. 



Lectures on Heat, Sound, and Light. By Richard 

 Wormell, D.Sc, M.A., Head Master of the City of 

 London Middle-Class Schools. (London : Thomas 

 iSIurby.) 

 The distinguishing feature of this book is its gradually 

 progressive character. The subjects are supposed to be 

 taken in the order in which they are given. " Heat being 

 far simpler in itself, and so much easier to explain, is 

 ]5laced first, while Light, being essentially more intricate 

 than either Sound or Heat, is placed last." The lectures 

 on Heat are adapted to the minds of pupils when first 

 receiving instruction in a scientific subject ; as the mind 

 develops the lectures advance in character, so as to make 

 full use of the increased intelligence of the pupil, and 

 ultimately, when light is reached, the perfection of the 

 undulatory theory can be presented with some hope of 

 its being appreciated. 



After each of the three parts questions are given, and, 

 what is far more valuable, a few pages of instruction 

 in laboratory practice. 



The book is illustrated by many figures, which are 

 often explanatory diagrams rather than pictures. Such 

 diagrams have far more educational value than cuts from 

 photographs of apparatus, but the want of proportion 

 may be carried so far as to give a misleading idea of what 

 a thing is really like— thus, the gridiron pendulum is 

 shown nearly as wide as it is long. 



There is a curious slip in Fig. 30, which shows how 

 waves travelling along paths differing by half a wave- 

 length come together again in opposite phases, and so 

 neutralise one another ; while, if there is a difference of 

 one or more complete wave-lengths, the phase is the 

 same, and they reinforce one another. The slip — it can 

 hardly be called more than a slip —consists in showing 

 the same number of wave-fronts in the longer as in the 

 shorter path. 



That the book should contain much that is excellent is 

 only to be expected of an author of such experience, 

 while the necessity for turning to such trivial details for 

 criticism is sufficient to show that fault of a serious kind 

 cannot be found. 



Une Experience sur I'Ascension de la Seve chez les 

 Plantes. Par Ldo Errera, Professeur h. I'Universit^ de 

 Bruxelles. Comptcs rendus de la Socidtd Royale de 

 Botanique de Belgique, torn. xxv. 2ieme partie, 1SS6. 

 This paper contains an interesting contribution to the 

 question of the course taken by the sap of vascular plants 

 on its way from the roots to the leaves. The view taken 

 by Sachs, that the current passes through the substance 

 of the lignified cell-walls, has, as is well known, been dis- 

 puted by Bohm, Elfving, and many others, who maintain 

 that it ascends through the cavities of the vessels and 

 tracheides. Various observers have endeavoured to bring 

 the question to an experimental decision by stopping up. 



