54 



SCIEXCE- G OSSIP. 



Elementary Practical Physics. By Professor 

 Henry Stroud. M.A.. D.Sc. xi + 281 pp., lh in. 

 x 5 in., with 115 diagrams. (London: Methuen i: Co. 

 3s. 6d. 



This book forms one of the series of text -books 

 on Technology edited by Dr. W. Garnett and Pro- 



- - r Wertheimer. of which some seven or eight 

 have now been published. Professor Stroud intro- 

 duces it as a book "intended to form an intro- 

 duction to practical work in a Physical Laboratory." 

 In reading through its pages one finds it somewhat 

 difficult to decide for what class of students the 

 work is intended. In some instances too much 

 knowledge is assumed on the part of the reader, if 

 the book is to be adapted to the requirements of 

 boys in an organised science school. The general 

 matter is well arranged and in good sequence ; the 

 chapters on specific and latent heats, and on Ohm's 

 law, being very concisely written. In a few cases 

 more care might perhaps have been bestowed on 

 details. For example,-on p. 43. in the experiment for 

 obtaining the density of a solid lighter than water, 

 allowance should be made for the fastening thread ; 

 on p. 61 we are not told for what particular sur- 

 faces is obtained the mean value of - 260 for the 

 coefficient of friction. On p. 228 a simpler form 

 than the Post Office pattern resistance-box should be 

 illustrated in describing a simple one for ordinary 

 purposes. If the beginner is not told of a simple one 

 he naturally would always ask for a P.O. pattern, 

 even in experiments on resistance by substitution. 

 Special mention is made on p. 239 of the Deprez 

 mirror galvanometer ; but the principal feature of 

 such an instrument, viz. that its readings are quite 

 unaffected by external fields of force, is entirely 

 ignored. Nevertheless the book will prove a helpful 

 one in higher schools and in colleges, especially if 

 the teacher can arive the student continued help. — 



•/- Q. 



Photography in Colours. By E. Child Bayley. 

 F.R.P.S. 74 pp. 7 in. x 5 in., with diagrams. 

 (London: Iliffe. Sons &Sturmey. Limited. 1900.) Is. 



This little book forms over seventy pages of 

 good spare-time reading. Written in a refreshing 

 manner, the subject is put forward without any 

 technicalities, and moreover without necessitatms 

 the reader being a photographer. The way is 

 paved with a good introduction upon the nature 

 of colour, and upon the wave theory of light. The 

 various colour processes are then described — viz. 

 Lippmann's interference method, the two three- 

 colour processes of Ives and Joly, and last, but 

 not the least interesting, the diffraction method of 

 Professor R. W. Wood, recently described by him 

 before the Society of Arts and the Physical Society. 

 The author reminds the reader at intervals that 

 the booklet treats of photography in colours, and 

 that photography in natural colours has not only 

 never been, but perhaps never will be, accom- 

 plished. — J. Q. 



Elementary Lessons in Electricity and Magnetism. 

 By Silyanus P. Thompson. D.Sc.. B.A.. F.R.S. 

 ix -r t52B pp.. 6§ in. x 4J in., with 291 illustrations. 

 (London and Xew York : llacmillans. 1900.) 

 4s. 6d. 



As this book is only another reprint of the 1895 

 edition, we are unable to call attention to any new 

 matter. Considering that it has been printed 

 upwards of twenty times since its first appearance 

 in 1881, and thai: it is still held as a standard 

 elementary text-book, too much cannot be said 

 upon its general excellence. 



Fr<x;-orchis in SUSSEX. — I send you herewith 

 a specimen of Habena . which I gathered 



at the foot of Beachy Head, near Eastbourne, on 

 the 16th of June this year. — (3/isx) E. Bray. Flair- 

 light House. HaiUham. Sussex. 



Pale-coloured Bee-orchis. — I found the 

 flowers of the bee-orchis abundant on the slopes 

 of Beachy Head, in Sussex, on 19th June, but they 

 were all very pale in tint, -ome almost colourless. 

 They are quite different from the beautiful flowers I 

 have found in other places. I do not know whether 

 the blooms of this orchis are always pale in tint on 

 Beachy Head, or if it is a peculiarity of this season. — 

 Thomas Hilton. 16 Kensington Place, Brighton. 



King and Botanist. — A writer in the -Echo 

 de Paris." in mentioning the simple kind-hearted- 

 ness of the King of Norway and Sweden, a recent 

 royal visitor to France, tells a story good enough 

 to repeat, even if not quite true. It is stated that 

 an eminent French botanist was collecting plants 

 outside Stockholm some time since, when he found 

 another gentleman similarly employed. They 

 struck an acquaintance and collected together for 

 a time, when the Frenchman proposed lunch. The 

 Swede replied, as his new friend was a foreigner 

 he should lunch with him. They sauntered along 

 until they arrived at the palace, which the King 

 entered, remarking : " I happen to be King of this 

 country, so cannot ask you elsewhere." Following 

 lunch, the afternoon was spent in discussing plants. 



The Fading of Birds' Eggs. — It is a curious 

 fact with most birds' eggs that in course of time, 

 certainly in a year or two. they begin to fade. Of 

 these some good examples are those of missel- 

 thrush, chaffinch, and lesser whitethroat. The 

 missel-thrush's eggs lose the clearness of then- 

 spots after a little time and become blurred, while 

 in the case of the latter two species the background 

 fades. The first theory, which will explain a good 

 many cases, but most of all the blue eggs, is that 

 the sunlight fades them, and this is especially so 

 with light blue eggs. There is no doubt about this, 

 and the collector is advised to keep his eggs away 

 from the light. There is, however, another theory 

 to put forward. If an egg is not thoroughly blown 

 clean, it will soon fade : therefore there must be 

 some explanation other than that of the light, 

 and the probable one is that the contents of the 

 egg contain sulphur, and if any is left behind it 

 will decompose, forming hydrogen sulphide. If 

 the egg is exposed to the air, the oxygen will de- 

 compose the hydrogen sulphide, forming sulphur 

 dioxide. which has, amongst others, bleaching 

 properties, and in time partially bleaches the egg. 

 This, of course, only refers to eggs not blown quite 

 clean. As some collectors are not very particular 

 on this point, this note may be useful to them. If 

 the eggs are thoroughly blown, immediately washed 

 out. and kept from the light, I do not think they 

 will suffer much from fading. — F. B. Ward, 11 

 Cranmer Boad. Grange Boad. Cambridge. 



