*76 



NA TURE 



[May 6, 1909 



An Explanation of ihe Adjustment of Ships' Com- 

 passes. By Commander L. W. P. Chetwynd, R.N. 

 Pp. 24. (London : J. D. Potter, 1909.) Price 2S. 

 This useful little book, the sections of which are 

 accompanied by diagrams, is an endeavour on the 

 part of the author to convey to the reader in as 

 concise a manner as possible the various causes of 

 deviation, and the methods of overcoming them, with- 

 out the use of mathematical formute. 



In most treatises dealing with this subject it is, un- 

 fortunately, the case that they are too theoretical and 

 contain too many symbols to suit the average seaman ; 

 therefore great praise is due to Commander Chetwynd 

 for the able manner in which he has brought out a 

 practical book for practical people. H. C. L. 



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.] 



An Inquiry concerning Scientific and Medical Journals. 



Can any of your readers kindly inform me where copies 

 of the following journals can be found in England, if 

 possible in London? 



(a) Lo Spallanzani. This is a journal of the medical 

 and natural sciences published at Modena in the 'seventies 

 and 'eighties. 



(b) Mitiheilungen d. Wiener embryol. Institiit. Pub- 

 lished in the 'eighties, and perhaps still. 



(c) Gazette medicate d'Algirie. Published at Algiers 

 in the 'fifties. 



(<i) Ann. Soc. mid. d'Emulation de la Flandre occid. 

 Roulers, 1849. There are other references to a Soc. mid. 

 d'Emulation, without place or name. I should be very 

 glad to have these Soc. mid. d'Emulation cleared up, as 

 there must, I think, have been several such societies. 



(e) Baltimore Sun, 1876. The stock of this journal was 

 burnt. Is there a file of it anywhere in England? 



(/) Archiv de med. nav. Published at Paris in the 

 'seventies. 



(g) Archiv f. Psych, u. Nervenkrankheiten, for the 

 'eighties. 



(h) Sociedad medica Argentina, 1901. 



fi) International Med. Magasinc. Philadelphia, 1S92. 



(;') Zeitschrift f. Tiermedicin, 1S97. (Sought at Royal 

 V'eterinary College.) 



{k) Soc. med. Wiirltemherg, 1905. ■ 



These have been sought for at the likely places, but it 

 is possible that they exist and have been overlooked. It 

 is a pity that some of the larger libraries in London dupli- 

 c.Tte certain of the rarer scientific and medical journals, 

 whereas by a division of material they might provide a 

 more comprehensive collection. Further, there ought to be 

 at least one library in London with a complete set of 

 university dissertations and degree theses. No library at 

 present appears to make a speciality of such material. I 

 have always found German university librarians most will- 

 ing to lend copies, but the delay is vexatious, and a cursory 

 examination of five minutes' duration would often have 

 settled the point required. Karl Pearson. 



Biometric Laboratory, LTniversity College, London. 



Radio-activity in Relation to Morozoff's Theory of 

 the Constitution of Atoms. 



The fact that the o particles of radium, as shown 

 lately by Prof. Rutherford and Geiger,' carry two 

 elementary charges of positive electricity, 2x4-65x10-'° 

 K.S.U. per atom of helium, appears quite unexpected, and 

 requires consideration. Since the atom of helium carries 



1 Proc. Rny. Soc, Ixx-xi., 162 (i()o8), and Pliysikalische Zeitschrift, x., 

 17 (1J09). Also Nature, November 5. 1908. 



more than a single charge, which would present the simplest 

 and most natural contingency, . there arises the question. 

 Why does it carry just two charges and not one or more? 

 an answer to which lias been proposed by N. L. Muller 

 in the " Jahrbuch der Radioalctivitat " (v., 702, 1908), 

 but it seems to me that the following explanation, based 

 upon the Morozoff theory of the constitution of atoms,' 

 will not be devoid of interest. 



According to Morozoff, all the chemical elements are 

 formed by manifold combinations of three primordial 

 elements, viz. archonium (nebulium) (Z), with a combining 

 weight 4 ; protohelium (x), with a combining weight 2 ; 

 and prolohydrogen (/i), with a combining weight i. 'Of 

 these, protohelium, as shown by the value of its com- 

 bining weight, presents half an atom of ordinary helium, 

 the re-combination of two of which yields again a helium 

 atom. 



.Archonium (Z), with its eight affinities, plays the part 

 of carbon in organic compounds, the archonium elements, 

 more or less saturated with protohelium (x) and proto- 

 hydrogen (/;), building the main atomic chain. The chains 

 of various chemical elements are built of one to eleven 

 such links, which, combined after certain rules, allow us 

 to reconstitute the whole periodic system of elements. 



As in the notation of organic chemistry, the atom of 

 radium is represented in Morozoff's system by the follow- 

 ing symbol :— 



-v - Z(x.,h) - {Z{xh\\ - {x„h)Z - X. 



Radio-activity is due to closing of the chain, accom- 

 panied by splitting off of two helium half-atoms (.v), 



Z(x2/0 - [Z(.v/()e]3 - ( V)Z + 2X. 



which yield the material carriers of electricity of the a 

 particles. 



Since both extreme helium half-atoms (x) are expelled 

 under similar conditions, and since they carry electricity, 

 each of them cannot carry less than one elementary charge 

 of 4-65x10-'° -E.S.U., hence a whole atom of helium 

 must carry at least two elementary electric charges, or 

 9-3 X io-'° E.S.U. 



As not only radium, but also thorium and uranium, are 

 represented by similar symbols, and their radio-activity is 

 always accompanied by the expulsion of two helium half- 

 atoms, it is evident that in all known radio-active changes 

 an atom of expelled helium must carry at least two 

 elementary charges. If we call, further,, as has been done 

 by Maxwell, an elementary charge an atom of electricity, 

 we can consider the combination of two of them as a 

 molecule of electricity, and state the following general 

 law : — in all radio-active changes the smallest quantity of 

 electricity associated with an atom of matter is not an 

 atom (4-65x10-'°), but a molecule of electricity 



(9-3X10-'"). B. DE SZYSZKOWSKI. 



Kieff, Zololoworotska 6, Russia, April 16. 



The Gravitative Strain upon the Moon. 



In his discourse on " The /Ether of Space " at the 

 Royal Institution, February 21, 1908 (abstracted in Nature, 

 vol. Ixxix., p. 323), Sir Oliver J. Lodge states that " the 

 force with which the moon is held in its orbit would be 

 great enough to tear asunder a steel rod four hundred miles 

 thick, with a tenacity of thirty tons per square inch," and 

 he further states that Maxwell calculated the gravitational 

 stress near the earth to be 3000 times that which the 

 strongest steel could stand, and near the sun it should be 

 2500 times as strong as that. 



For convenience we may call the diameters of the earth 

 and of the moon Sooo and 2160 miles respectively, and 

 the moon's distance from the earth 240,000 miles. At 

 the surface of the earth the moon would fall 16- 1 feet, or 

 1/328 mile, in one second. The velocity necessary to 

 counteract this fall is, therefore, equal to v'Sooox 1/328, 

 or about five miles per second, at which velocity the 

 centrifugal force of the moon, revolving at a distance of 



1 /'/lysicai J!<7'if7U (Ru 



n), i 



■ (1308 



NO. 2062, VOL. 80] 



I 



