140 



NA TURE 



{June 16, 1881 



molecule is nowhere defined \m. a note on p. 57 a casual 

 statement is made as to the meaning of the term) ; 

 " Avogadro's law," which lies at the basis of the whole 

 modern edifice of chemistry, is conspicuous by its 

 absence ; certain statements as to gaseous combination 

 and to "volume weights " are made, it is true (p. 35), but 

 these are incomplete and misleading. 



When a theory of valency is raised on so slender and 

 shifting a molecular foundation as is here laid, no wonder 

 that the edifice should be a strange one ; the definition of 

 "atomicity" on pp. 54-55 is incomplete, and cannot be 

 upheld by facts ; the statement on p. 5S, "it is then a 

 law to which there are no real exceptions, that though 

 the equivalence of an element may vary, it does so always 

 by the addition or subtraction of an even number," is 

 simply untrue. As an "important conclusion" from 

 certain "facts" (? fancies) "on equivalence," it is stated 

 that (p. 59) "a formula which possesses an uneven 

 number of bonds or units of chemical affinity cannot 

 possibly represent a molecule " ; without minutely criti- 

 cising the expression " bond or unit of chemical affinity," 

 suffice it to say that such a formula as, according to Dr. 

 Kemshead, cannot possibly represent a molecule, un- 

 fortunately does represent a molecule. The existence of 

 the molecule NO is a case in point : a propos of this 

 compound, there is a charming example of the author' s 

 method of treating chemical science as a collection of 

 opinions of various authorities to be found in a footnote 

 on p. i6g. 



Notes on tJie Crania of Ncui England Indians. By 

 Lucien Carr. From the Anniversary Memoirs of the 

 Boston Society of Natural History, 18S0. 



This is one of the numerous contributions now being 

 made towards our knowledge of the fast-disappearing race 

 of North American Indians. The author, Mr. Lucien 

 Carr, holds the office of Assistant Curator to the valuable 

 Museum of American Archeology and Ethnolog) at 

 Cambridge, Mass., an institution owing its foundation to 

 the liberality of Mr. Peabody, so well known in England 

 by his benefactions to the London poor, and its scien- 

 tific excellence to the zeal and organising power of its 

 first curator, the late Dr. Jeffries Wyman, and of his 

 successors. 



The object of the present memoir is to collect together 

 such information as is still to be obtained regarding the 

 cranial characters of the native Indians of the N ew England 

 States, the celebrated " five nations " of the early his- 

 torians of America, who in consequence of their geographi- 

 cal position were among the first of the race to succumb 

 to the inroads of European immigration. Measurements 

 are given of 67 crania, of which 38 are assigned to males 

 and 29 to females. The averages of these measurements 

 give the following results : — A medium cranial capacity, 

 i.e. 1436 cubic centimetres for the males and 1319 for the 

 females. A latitudinal index of -759. showing mesati- 

 cepLalism verging upon dolichocephalism. The alti- 

 tudinal index exactly the same. The principal facial 

 indices show orthognathism, with a strong tendency 

 to mesognathism, a mesorhine nose (index 50), and 

 slightly megaseme orbits (index 88 in the males, and 

 91 in the females). Although these are the average cha- 

 racters of the whole collection, very few, if any,"of the 

 individual crania are to be found presenting them. There 

 IS indeed no such uniformity among these skulls as may 

 be seen in certain races, such as Eskimos, Bushmen, 

 Fijians, Andamanese, or e\'en Australians. Perhaps it 

 could scarcely be expected in inhabitants of a large 

 continent, presenting great diversities of climatic and 

 other conditions, and with no natural barriers to free 

 migration and intercourse. The examination of these 

 skulls therefore confirms what has been often remarked 

 before, that although in a broad sense the American 

 Indians present a certain community of type, there is 



great diversity in detail among them, the result probably 

 of a long series of repetitions of the process of breaking 

 up into distinct groups or tribes and reuniting in various 

 combinations. 



LETTERS TO THE EDITOR 

 \Tlie Editor does not hold himself responsible fm- opinions expressed 

 by Ins correspondents. Neither can he undertake to return, 

 or to correspond laith the writers of, rejected vianusiritts. 

 No notice is taken of anonymous communications. 

 [ The Editor urgently requests correspondents to luep tluir letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible o/hei-,vise to ensure the aptearance even 

 of communications containing interesting and ncvel facts.'\ 



The Conservation of Electricitj 



In a recent communication to Nature (vol. xxiv. p. 78) 

 Prof. Silvamis P. Thompson very kindly mentions my latest 

 memoir on "The Conserv.ition of Electricity," and, as I am 

 glad to find, confirms my views on this subject by stating that he 

 has in'iependently arrived at the .'^ame conclusions with myself. 



As regards however the question of priority moved by Prof. 

 Thompson, I think I ought to add that an earlier paper of mine, 

 published five years ago, mu^-t have escaped Prof. Thompson's 

 atteniion. This was printed as an abstract in the Comptes rendus 

 of the Paris Academy of Sciences for June 19, 1876, under the 

 title, " Extension dii prhicipe de Carnot a la theorie des pheno- 

 menes electriques. Equations differentielles generales de I'equi- 

 libre et du mouvement d'un sj'steme electrique reversible quel- 

 conque. " I there enunciated the law of the Conservadon of 

 Electricity in the same terms as now, and also gave the same 

 analytical method for applying it. 1 beg leave to quote as a 

 proof the following explicit passage from this extract : — "L'equa- 



tion /«'ot = o a une autre signification plus simple; eUe signifie 



que de I'electricite pent se deplacer, mais ne peut jamais varier en 

 quantite. Ce priucipe de la conservation de la quantite d'elec- 

 tricite a ete admis par les physiciens dans tous les cas connus 



jusqu'ici, influence, froltemeni, etc Pour que Idm^o 



pour tout cycle feruie, il fiiut que dm soit uue differentielle par- 

 faite." This method 1 had already applied in 1S75 to the 

 phenomena presented by mercury electrodes (vide Annates de 

 Chini. Phys. 1875), -1" ^'^ct my latest memoir is merely a re- 

 newed attejjpt to draw, by means of new applications, the 

 attention of physicists to a fact which I cannot help considering 

 as important for the future, viz. tliat the principle of the Con- 

 servation of Electricity is, as far as analytical applications are 

 concerned, the exatrt analogue to Carnot's Principle for Heat. 

 Pari-, Faculte des .Sciences, June 5 G. Lippmann 



Apparent Decomposition of Sunlight by Intermittent 

 Reflecting Surfaces 



It occurred to me that light might be decomposed by inter- 

 rupting, with a reflecting surface, a ray of light in .such a manner 

 that the interruptions may be proportional to the wave-length 

 period of any particular ray forming a p.art of a composite ray. 

 The expeiimeiit is effected in the following way : — 



A wheel having bright spokes (the large wheel of a bicycle 

 answers veil) is caused to revolve between an observer and the 

 sun, so that a ray of light is reflected to the observer by a bright 

 spoke; then, when 120 spokes pass before die ob-.erver per 

 second, violet light shines out vividly ; when 65 pass, red 

 appears, and diffeTent rates of revolution give different colours. 

 There seems to be a marked relarionship existing: between the 

 number of spokes which pass by and the wave-length of the 

 two C'jlours mentioned, that of the violet being uuTire inch, and 

 that of the red ^ ^ ?, , -, inch. 



I am now investigating this apparent relatiom-hip between 

 spoke-interruption and wave-length for the other colours of the 

 spectrmn of white light, and I hope to be able to make known 

 the results shortly. Frederick J. Smith 



Taunton, June 4 



Symbolical Logic 

 I AM sorry that Mr. MacColI should have thought that there 

 was any intention on my part to suggest a doubt as to his having; 



