Februarv 15, 1906J 



NA TURE 



565 



Elements of Applied Microscopy. By Charles-Edward 

 Amory Winslow. Pp. xii+183. (New York: John 

 Wiley and Sons ; London : Chapman and Hall, 

 Ltd., 1905.) Price 6s. bd. net. 

 Tins little book is planned on novel lines, and con- 

 tains a good deal of information in a small compass. 

 As it is primarily intended for class use, practical 

 details are briefly dealt with, and more space is thus 

 available for descriptions of the various objects which 

 the microscopist is intended to study. The first three 

 chapters deal with the theory, construction, and 

 manipulation of the microscope, and the preparation 

 and mounting of objects. Next, micrometry and tin- 

 camera lucida are described, and the subsequent 

 chapters are devoted to the microscopy of starches, of 

 foods and drugs and their adulterants, the examin- 

 ation of textile fibres and of paper, forensic micro- 

 scopy, microchemistry, and petrography and metallo- 

 graphy. Sufficient information is given to stimulate 

 the student's powers of observation and desire for 

 further knowledge. The chapter on the microscopy 

 of paper is a particularly good one. Altogether the 

 book should usefully fulfil the object for which it has 

 been written. 



Auslese cms meiner Unterrichts- und Vorlesungs- 

 praxis. By Dr. H. Schubert. Zweiter Band. 

 Pp. jiS. (Leipzig: Goschen, 1905.) Price 4 marks. 

 Tins is a very entertaining instalment of Prof. 

 Schubert's lectures. The first section deals with 

 triangles having rational sides and areas, pyramids 

 with rational edges and volumes, and similar subjects. 

 Tables and formula 1 are given which will be useful 

 to those who wish to set neat numerical exercises in 

 trigonometry and mensuration. Section ii. is devoted 

 in continued fractions, the Pellian equation, expression 

 of an integer (when possible) as the sum of two 

 squares, and so on. Section hi. is on the elementary 

 calculation of logarithms, and forms a supplement to 

 a similar chapter in the first volume. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications .] 



Secondary Rontgen Rays and Atomic Weight. 



In papers oh secondary Rontgen radiation and polarised 

 Rontgen radiation I have shown that all the phenomena 

 of secondary radiation (as indicated by an electroscope 

 placed, several centimetres from the radiator) may, from 

 substances of low atomic weight, be accounted for by con- 

 sidering the corpuscles or electrons constituting the atoms, 

 to be accelerated in the direction of electric displacement 

 in each primary Rontgen pulse as it passes through such 

 substances, and that the interaction between the corpuscles 

 affects only to a small extent the character of the secondary 

 radiation proceeding from the substance. In light atoms 

 there is almost complete independence of motion of the 

 corpuscles within the limits of disturbance produced by all 

 primary beams experimented upon. 



It was also shown (Nature, March 9, 1905) that this 

 independence of motion disappears in heavier atoms in 

 which there may be conceived to be a more intimate re- 

 lation between the corpuscles, inter-corpuscular forces 

 being brought into play which have the effect of widening 

 the secondary pulses and producing accelerations in the 

 corpuscles in directions other than those of electric dis- 

 placement in the primary pulse. Until recently I have 

 been unable to make experiments on a sufficient number 

 of elements of higher atomic weight to arrive at any law 

 connecting the penetrating power oi the secondary radi- 



NO. 1894, VOL 73] 



ation with the atomic weight of the radiator. Recent 

 investigation has, however, shown that beyond the region 

 of atomic weights in which the character of secondary 

 radiation is almost independent of the nature of the 

 radiator, the absorbability of the radiation is a periodic 

 function of the atomic weight, the periodicity agreeing so 

 far as these experiments have gone with the periodicity in 

 chemical properties. 



A detailed account of these results will be published 

 shortly. 



They, however, afford striking evidence of a connection 

 between chemical properties and distribution of corpuscles 

 in the atom, such as Prof. J. J. Thomson suggests in his 

 conception of the constitution of the atom ; for the 

 character of the secondary radiation set up by a given 

 primary can only, according to the theory which hasbeen 

 shown to account for all the phenomena I have hitherto 

 observed, be affected by the relation between the radiating 

 corpuscle and its neighbours. 



The results also suggest a method of determining atomic 

 weights by interpolation, for a small variation in atomic 

 weight is usually accompanied by a very considerabli 

 change in absorbability of the secondary radiation, and 

 though in these experiments great accuracy has not been 

 essential, it appears that in many regions a variation oi 

 atomic weight by much less than 1 would be indicated. 



The experiments are being continued. 



Charles G. Barkla. 



University of Liverpool, February q. 



The Falkland Island Fox. 



Is a review in the current number of Nature of Mr. 

 Renshaw's " Some Mammalian Types," reference is madi 

 to the "Antarctic wolf of the Falkland Islands extermin- 

 ated by the sheep farmers in sill defence." Might f be 

 permitted to add a word on this subject in correction of an 

 erroneous impression current among many naturalists with 

 regard to this animal? During a visit to the Falkland 

 Islands in 1903, and again in 1004, I made careful in- 

 quiries with regard to the native wolf or fox. The oldest 

 sheep farmers in the islands, men who remembered when 

 the fox was still plentiful, insisted that it was quite a 

 mistake to credit it with attacking sheep: this never 

 occurred, and the reason that the farmers waged war 

 against the foxes was because the sheep, apparently mis- 

 taking them for dogs, especially at night, in their terror 

 ran into the bogs and swamps which abound in the islands 

 and were consequently lost. None of the farmers whose 

 experience went back to the time of these foxes had any 

 memory of sheep being killed or even mauled by them. 

 In making this correction, I must say that I have not seen 

 Mr. Renshaw's book, and consequently do not know what 

 reason he attributes for the extermination of the fox. 



R. N. Rudmose-Brown. 



Seottish National Antarctic Expedition, Edinburgh, 

 Februarv 10. 



Chinese Names of Colours. 



Ox the interesting observation on Chinese names of 

 colours of Mr. H. Crook, in Nature (January 11), 1 

 would add this little information. Prof. Giles in his 

 great dictionary gives (No. 4S45) 1g =pf as " a very light 

 violet colour"; Wells Williams (p. 820) as "a purple 

 colour." Mr. de Zelinski and Cl£mence Royer, in an 

 interesting note " Sur les noms des couleurs en japonais " 

 (" Congres internat. des Orientalistes, Compte rendu de 

 la iere session, Paris, 1873, vol. i., pp. 83-87), give 

 another example, in Japanese, of the same kind. 



J* i<- 'asagi), literally "a light yellow," signifies, fol- 

 lowing Prof, de Rosny, " bleu de ciel " ! Mr. Hepburn, 

 in his Japanese dictionary, fifth edition, Tokyo, 1894, 

 renders the same expression by " a light green or pale 

 colour." 



Analogous oddities can also be £e»nd in European 

 languages, as the French " azur cendre," or " une rose 

 (the flower) jaune," &c. Giovanni Vacca. 



Firenze, Via Ricasoli 49, Italy. 



