;i6 



NA TURE 



[August 6, 1908 



observations are concerned, and in two respects the 

 book shows considerable advance. Thus twelve pages 

 are devoted to the Campbell Stokes sunshine recorder, 

 and full instructions for setting the cards and adjust- 

 ing the instrument are given, although the measure- 

 ment of sunshine is not mentioned in the old book. 

 Also the doubt about the measurements of wind 

 velocity by the Robinson anemometer and the re- 

 lation between the recorded velocity and the numbers 

 of the Beaufort scale has been to a great extent 

 removed. A useful classification of the scale, 

 and a description of the results produced both on sea 

 and land by the winds denoted by the various num- 

 bers, are given. Notwithstanding this, a man must 

 be more than human if his estimation is entirely free 

 from the influence of the prevailing conditions to 

 which he has recently been exposed. A scale of fog 

 intensity based on the inquiry supported by the 

 London County Council in the winter of 1902-3 is 

 also given. 



Feinman 's nephoscope and Besson 's comb nephoscope 

 are described. Probably the authors are not to blame, 

 but it is a pity that cloud velocities are not measured in 

 angular velocities, or lather angular velocities reduced 

 to the zenith, the tangential velocity of the handbook. 

 Certainly angular velocity is the only physical quan- 

 tity in which cloud motion as seen from a single 

 station can be expressed. It seems absurd, and is 

 certainly very far from the truth, to assume that all 

 clouds are at a height of 1000 metres, or that all 

 clouds are moving with a linear velocity of i metre 

 per second. Why, too, should the term " relative " 

 be used? If relative means angular, as appears 

 from the context, its use is incorrect, and although 

 sanctioned by past usage, it would be well to give up 

 the incorrect use of a technical word. 



In the chapter dealing with the corrections to be 

 applied to the barometer, it might have been well to 

 point out that the reading in windy weather is to 

 some extent dependent on the position of the room, 

 and the way in which openings from it are situated 

 with regard to the wind direction. There is plain 

 evidence that an important error may be so produced. 

 The appendices consist of the usual tables and a 

 memorandum by Dr. Shaw on the important question 

 of units. In it Dr. Shaw points out the objections to 

 both the systems now in use. To avoid the trouble 

 of negative temperatures he advocates the use of the 

 absolute centigrade scale, omitting the first figure, 

 which will almost always be 2. This would be a 

 vast improvement, and would earn the gratitude of 

 all who have to obtain mean temperature values for 

 places in temperate latitudes. In addition to the 

 question of » negative values, the muddle of having 

 two systems is most pronounced in the case of tem- 

 perature, for the alternative values cannot be read 

 off from a slide-rule, as they may be for the barometer 

 and the rainfall. An entirely fresh system has per- 

 haps a better chance of general adoption than either 

 of those now in use. 



The handbook is carefully prepared, and contains 

 much interesting matter, and Mr. Lempfert is cer- 

 tainly to be congratulated on its publication. 

 NO. 2023, VOL. 78] 



SOME PHYSICAL TEXT-BOOKS AND 

 LECTURES. 

 (i) Theorie der Elektrizitdt. Vol. i., Einfiihrung 

 in die Maxwellsche Theorie der Elektrizitat. By 

 Dr. A. Foppl. Third edition, edited by Dr. M. 

 Abraham. Pp. xviii-l-460; illustrated. (Leipzig: 

 B. G. Teubner, 1907.) Price 12 marks. 



(2) Kleiner Leitfadcn der praktischen Physik. By Dr. 

 F. Kohlrausch. Second enlarged edition. Pp. 

 xviii + 268; illustrated. (Leipzig and Berlin: B. G. 

 Teubner, 1907.) Price 4 marks. 



(3) Die Stimnigabel: Hire Schwingungsgesctze imd 

 Anwendungen in der Physik. By Dr. E. A. Kiel- 

 hauser. Pp. viii+i8S; illustrated. (Leipzig: B. G. 

 Teubner, 1907.) Price 6 marks. 



(4) Liift, Wasser, Lirht und Wdrtnc. By Dr. R. 

 Blochmann. Third edition. Pp. vi+149; illus- 

 trated. (Leipzig : B. G. Teubner, 1907.) Price 

 1.25 marks. 



(5) Molekiile, Atome, Weltdther. By Dr. G. Mie. 

 Second edition. Pp. iv-l-142; illustrated. (Leipzig: 

 B. G. Teubner, 1907.) Price 1.25 marks. 



(6) Die Stellung der Physik zu den Naturwisscn- 

 schaften und der Technik. By Aug. Hagenbach. 

 Pp. 25. (Leipzig : B. G. Teubner, 1907.) Price 

 o'So mark. 



(i) /^^ F this group of volumes the first is un- 

 ^-^ doubtedly the most important. Since, how- 

 ever, it is the third edition which is before us, and 

 very few changes have been made, it calls only for a 

 short notice. These changes consist of alterations in 

 the arrangement of the matter and a revision of the 

 text here and there wherever it was found possible to 

 make the exposition clearer. These changes have been 

 made under the editorship of Dr. M. Abraham. The 

 result is to improve a book of exccptionallv high 

 standing. We do not hesitate to affirm that we have 

 in it one of the best expositions of Maxwellian doctrine, 

 and at the same time one of the best introductions to 

 vector analysis. 



(2) This also is an improved edition (the second). 

 For a " smaller " text-book it contains an enormous 

 amount of information useful for general reference. 

 This information is necessarily very condensed. In 

 some cases it will probably be found insufficient bv 

 anyone except an expert experimentalist; that is to 

 say, by one (for example, a chemist) who, though pro- 

 ficient in laboratory work, is not acquainted speciallv 

 with practical physics, and wishes for hints in regard 

 to physical processes. 



(3) A monograph on the tuning-fork and its applica- 

 tions is a very welcome addition to physical literature. 

 This one is based upon about eighty original papers 

 published mainly since 1S70; these lie within the period 

 during which most work on this instrument has been 

 done. When it is stated that the volume is non- 

 mathematical, it will be obvious that it does not by 

 any means profess to be complete ; it will also be 

 understood how it is that there are only two references 

 to Lord Rayleigh in it, and that his " Theory of 

 Sound " is not quoted in the list of consulted books 

 at the end. This limitation in the treatment excludes 

 many of the most interesting problems in connection 



