December i6, 1915] 



NATURE 



437 



it need be if the output were on a large scale. One 

 )f the well-known Detroit firms is said to have a 

 20-h.p. tractor, built on the usual lines of the cheap 

 American car, which can be delivered in this country 

 ;or 70Z. In the reorganisation of agriculture which 

 Lord Selborne has recently declared to be necessary 

 after the war, it is certain that such labour-saving 

 devices will play a leading part, and it will be a 

 pity if this market cannot be held for our own manu- 

 facturers. It seems probable that in the future the 

 demand for pleasure cars will not suffice to keep the 

 existing motor works fully employed, and here is a 

 field in which the manufacturer who has the necessary 

 courage and foresight will reap a rich harvest. 



In a paper on storm frequency changes in the 

 United States {Monthly Weather Review, August, 

 19 15, xliii.) M. Henryk Arctowski touches on the 

 problems of the relations of sun-spot activity to the 

 terrestrial atmosphere. His discussion is based on 

 the number and course of the low-pressure areas which 

 crossed the meridian of ioo° W. in the United States 

 from 1883 to 1913. There were six storms fewer 

 per year during the years of sun-spot minima than 

 during the years of sun-spot maxima. This agrees 

 with KuUmer's conclusion that years of sun-spot fre- 

 quency are stormier than those of sun-spot minima, 

 but in this case the increase was only 6-i per cent. 

 The difference in distribution throughout the year was 

 much greater. Years of sun-spot minima were char- 

 acterised by a more uniform latitude distribution 

 throughout the year. During years of sun-spot 

 maxima, on the contrary, the latitude distribution 

 is more unequal, being to the north in February, Sep- 

 tember, October, and particularly November, and to 

 the south from February to May. The action of the 

 increase of sun-spots upon storms seems to be primarily 

 one of co-ordination, and the conclusion is that the 

 annual variation in the geographical distribution ci 

 atmospheric pressure must be essentially different in 

 the years of sun-spot maxima from that during years 

 of sun-spot minima. 



Modern mathematics has reached such a high 

 degree of complexity and specialisation that only the 

 shortest and simplest papers appeal to an extended 

 class of readers. The Edinburgh Mathematical 

 Society, in addition to its Proceedings, is now 

 P' liodically publishing " Mathematical Notes," edited 

 by Dr. G. D. C. Stokes, and printed by Lindsay and 

 Co., Edinburgh. The contents consist mainly of 

 .lUirnative proofs of formulae in elementary text- 

 books, much on the lines of similar work in the 

 Mathematical Gazette ; and on p. 193 we regret to 

 note the presence of a divisor " sin 90° " in a problem 

 on the solution of a right-angled triangle, an element 

 the introduction of which should necessitate a deduc- 

 tion of marks by any examiner if he is really com- 

 petent. Again, symbols and triangles figure to an. 

 extent suggestive of the predominance of similarly 

 named instruments in the concert given in 1908 to the 

 Mathematical Congress at Rome. We have men- 

 tioned the Mathematical Gazette, and it now remains 

 to direct attention to a fly-sheet issued in the recent 

 copy of that journal (October, 1915) headed " Books, 

 NO. 2407, VOL. 96] 



I etc., Received," containing a long list, not only of 

 i boc^ks, but also of periodicals, with lists of titles of 

 contents. This list, while occupying little more than 

 three pages of small print, meets a distinct want. 

 1 Similar lists have previously been published in the 

 ' Bulletin of the Calcutta Mathematical Society, and 

 \ their utility has been fully recognised in these 

 i columns, but unfortunately these lists have usually 

 I been several years in arrears. At the same time, the 

 ; fact that this list (if we have not made some over- 

 sight) does not contain a single paper on the mathe- 

 matics of the aeroplane must be regarded, not only 

 as an anomaly, but as a serious indictment against 

 ! mathematicians. 



i The December number of Scientia, although less 

 bulky than in pre-war times, falls in no degree behind 

 j its predecessors in point of interest. In an article on 

 j the constitution of the luminous atom, Prof. Fabry, 

 of the University of Marseilles, shows how, in seeking 

 a suitable model which would have the radiating 

 i powers of the atom, it has been necessary to leave the 

 I classical dynamics, and that two paths have been 

 I opened up. In the first, due to Ritz, the active element 

 I of an atom is taken to be a small magnet about 

 j which an electron moves in a closed orbit. In the 

 j second, due to Bohr, the Rutherford atom — a 

 ; central concentrated positive nucleus about which a 

 \ number of electrons move as in a planetary system — 

 ! is taken, and the difficulty that such a system would 

 radiate its energy too rapidly, avoided by assuming that 

 ! the energy is sent out only in bundles or quanta. By 

 this means the spectra of hydrogen, helium, and other 

 i less simple substances have been reproduced with 

 : startling accuracy. In another article Prof. Bragg 

 : shows how X-ray spectroscopy sheds light on the con- 

 stitution of crystals, and in a different field Prof. 

 I Ramsay Muir's article on the problems of the future 

 ! peace, and Prof. Fedozzi's on the lessons the war has 

 I taught with regard to the treatment of foreigners 

 I domiciled in a country, will be read with interest. 



I A PAPER on the harbour and coast defence works at 

 j .Alexandria, Egypt, was read at the Institution of Civil 

 j Engineers on November 30 by Mr. D. E. Lloyd-Davies. 

 j The city possesses two harbours, the western being 

 I under the jurisdiction of the Egyptian Government, 

 1 and the eastern is being developed by the municipality. 

 I The first improvement of the access to the port was 

 ! undertaken in 1889; the Gabbary dry dock was built 

 in 1900, and important extensions were completed in 

 191 1 at a cost of 282, 770^., about 50,000/. less than 

 the value of the lands reclaimed. The western port 

 now ranks third, after Marseilles and Genoa, among 

 the Mediterranean ports ; it has 1850 acres of sheltered 

 area capable of accommodating 250 large vessels 100 

 yards apart. The value of import and export trade 

 rose from 18,856,000/. in 1880 to 52,075,000/. in 1908, 

 and the revenue in 191 1 reached 325,000/. Since 1906, 

 when the author was appointed city engineer of Alex- 

 andria, the construction of breakwaters at the mouth 

 of the bay has been proceeded with. These provide a 

 fine pleasure harbour of 600 acres, an additional refuge 

 for light commercial craft, and serve the purpose of 

 protecting the sea-wall. 



