February, 1907.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



45 



Observations and Investigations made at the Blue Hil 



Meteorological Observatory, Massachusetts, U.S.A.. in the 

 years 1903 and 1904, undi.r the direction of A. Lawrence 

 Rotch (Cambridge, 1906; 410. 74 pp.).— The Blue Hill Ob- 

 servatory- was founded by .Mr. Rotch on January 30, 1885, 

 and the main object of its existence is scientific research. 

 Intimate relations have been cultivated with foreign meteoro- 

 logists and institutions, and Mr. Rotch has attended the 

 .Meteorological Conferences held in Europe, and the meet- 

 ings of the International Cloud Commission and of the 

 Commission for Scientific .\eronautics, of both of which he 

 is the American member. The exploration of the air by 

 means of kites and lifting instruments, which record continu- 

 ously, was originated at Blue Hill in 1.S94, and great atten- 

 tion' has been paid to this subject ever since. The present 

 volume (which forms Part H. of Vol. LVHI. of the AnnaJs 

 of the Asironcmical Observatory of Harvard College) con- 

 tains the observations made twice daily in the years 1903 

 and 1904, and also the results from the kite meteorograph 

 and simultaneous records at the ground. In addition there 

 are the following papers : — (i) Unusual Sky-Colours, by 

 Mr. -A. L. Rotch; (2) The Effect of .Meteorological Condi- 

 tions upon Optical Refraction in the Lower Atmospheric 

 Strata, by Mr. L. .\. Wells; and (3) The Errors of Absorp- 

 tion Hygrometers, by Mr. S. P. Fergusson. 

 MICROSCOPY. 

 The Principles of Microscopy, by Sir .\. E. Wright, ^LD., 

 F.R.S., &c. (London : .\. Constable and Co., Ltd., 1906, 

 xxii. and 250 pp., iS plates and 97 figs, in text; price 21s. 

 net.). — With Sir A. E. Wright's intention in writing this 

 book we are in complete sympathy. There can be no doubt 

 that users of the microscope as a body are content with too 

 much ''rule of thumb " and too little " reasoned action," 

 and that they fail accordingly to get the best results out of 

 their instruments, even where such results are imperatively 

 necessary to them. In endeavouring to persuade the worker 

 with the microscope that his methods are capable of im- 

 provement, and in leading him up to such improvement by 

 a careful enunciation of principles, based upon demonstra- 

 tion and experiment, Sir .\. E. Wright has done much- 

 needed work. It is, however, somewhat doubtful whether 

 he has not over-shot the mark and gone over the heads of 

 the larger audience whom he would no doubt have wished 

 to reach. In the first place, the book, beautifully printed 

 and illustrated though it is, is unquestionably costly, and 

 this alone would limit its usefulness ; in the second place, it 

 may be questioned whether it does not deal too much with 

 principle and too little with practice to attract the average 

 worker. In this connection it must be borne in mind that 

 the book is admittedly written for the " rule of thumb " 

 worker, and not for the student of microscopical optics, but 

 the average worker, unfamiliar with optics, would find it 

 dillicult to follow or appreciate the sequence of the reason- 

 ing, or to realise where he was to get his equivalent return 

 for the " intellectual effort " which the author demands of 

 him. The method of dealing with the subject is unfamiliar, 

 and the phraseology, and sometimes even the words, more 

 unfamiliar still, but the experiments are of the simple and 

 easily performed, yet ingenious and instructive, character 

 which we have learned to expect of the author. The optical 

 principles, however, gain largely as addressed to the 

 ordinary reader, from an almost entire avoidance of mathe- 

 matic.'il expression, and the exposition of them leaves upon 

 the technical reader an impression of much originality. It 

 is in the practical ap|)lications of the theories so carefully 

 built up that the worker will find most disappointment, 

 inadequacy, and in some instances even misdirection, as 

 where he is instructed (on p. 174) to use a plane mirror 

 with the sub-stage condenser with daylight, and a concave 

 mirror with lamp-light ; to obtain a " sharper " image by 

 cutting down the condenser beams " severely " with the 

 diaphragm ; and by statements that a too thin cover-glass is 

 corrected for by shortening the body tube, and a too thick 

 one by lenethening it (p. 20^). The author appears to con- 

 sider the .\bbe condenser witVi its enormous spherical and 

 chromatic aberrations as effective as an aplanatic .and 

 achromatic condenser, and vet we see him in Chapter xv. 

 endeavouring to get rid of the aberrations caused by the use 

 of the former condenser combined with a concave mirror 

 and an incandescent l.imp, by culling down the beams from 



the latter by a screen placed immediately before it, the 

 lamp being apparently placed so close to the microscope as 

 to be in the principal focus of the concave mirror. Methods 

 of measuring the magnification of an object — though atten- 

 tion is not called to this — and the magnifications of ob- 

 jectives and eyepieces are dealt with in original ways, which, 

 however, seem to us to have no superiority over the better- 

 known but untouched-on methods. The author very frankly 

 expresses his indebtedness to Mr. J. W. Gordon for much 

 help and suggestion, but undue prominence would seem to 

 be given to the latter's very interesting and ingenious, but 

 noiie the less still debatable, theories. In particular, it 

 would have been well if Sir A. E. Wright had laid greater 

 stress on the limitations of Mr. Gordon's much-advertised 

 method of improving the image given by high-power 

 oculars, and his own appraisement of the " achievement " 

 that it may " carry us to a higher limit of resolution " by 

 enabling the optician to correct his lenses somewhat more 

 easily! It would save much irresponsible talk as to a 

 newlv-realised magnification of 10,000 diameters, coupled 

 with suggestions that Mr. J. Butler Burke's " radiobes " 

 should be inspected by them without delay I 

 PHOTOGRAPHY. 

 The Complete Piiotographer, by R. Child Bayley 

 (London: .Methuen and Co.; price los. (>d. net.). — This is 

 the fourth volume of a series of which " The Complete 

 Motorist," "The Complete Golfer," and "The Complete 

 Cricketer," are the other three, but there is nothing of a 

 sporting character in it. It is a straightforward treatise, 

 beginning with historical matters and concluding with 

 chapters on pictorial photography, exhibitions, and societies. 

 It is neither an instruction book nor a guide to the science 

 of the subject ; it includes, as the author himself says in the 

 preface, very few formulae, and yet it contains a great deal 

 ot information .set down in a rather diffuse, but eminently 

 readable style. Every few pages there is a reproduction of 

 a notable photograph, printed on special paper, and of these 

 there are more than sixty, intended presumably to show the 

 reader some of the best work, that he may know the sort 

 of result that he should aim at. The frontispiece is a fine 

 photogravure portrait of Henry Irving, by William 

 Crooke. After about four hundred pages of subject matter 

 there follows a very copious index. .As already stated, it 

 does not claim to be what is generally understood as a 

 student's book. He who seeks information on any particular 

 subject will almost certainly find a suitable entry in the 

 index, and on turning to the page indicated he may learn 

 much, but, on the other hand, he may find that the subject 

 is merely talked round, or that it is summarily dismis.sed 

 with a mere reference, or an expression of disapprobation. 

 The author holds some views that other authorities would 

 regard as unsound, as, for example, that levels on hand 

 cameras are of very little use because they cannot be seen 

 at the same time as the finder, and that for architectural 

 work they arc not sensitive enough. Doubtless, this is oc- 

 casionaliv true, because of bad design or inferior workman- 

 ship, but it ought not to be so. On the whole, the advice 

 given is good, and in those cases where one is inclined to 

 disagree with it, it is entitled to respectful consideration 

 because of the experience of the author. Those who like 

 reading about photographic methods and similar subjects, 

 and arc tired of the innumerable little guide books that are 

 constantly being produced, will appreciate this volume, for 

 it is essentially a book to be re.ad, rather than a work of 

 reference. 



ZOOLOGICAL. 

 We have to acknowledge the; receipt of a copy of an article 

 0:1 •• Snake Feeding at the Zoo," reprinted from the January 

 number of the Humaiiifarian Hcvinr. The practice ot 

 feeding these reptiles with living animals is strongly con- 

 d'^mned ; and it is urged, on the authority of the Director 

 of the New York Zoological Park, that " dead meat " will 

 equally well serve the purpose. 



MISCELLANEOUS. 

 The Scientist's Pocket Book and Di.iry (James WooUey, Sons 

 aivl Co., Ltd.. M.inchester ; is., cloth; (k1., pajxT cover). — 

 This is a capital little book, containing a number of useful 

 tables in all branches of science, and a diary with a week on 

 a page. 



