April 22, 1920] 



NATURE 



243 



It is pointed out that the investigations at the Bureau 

 have led to a vast improvement in the constancy and 

 trustworthiness of thermometers and in the measure- 

 ment of atmospheric pressure, and it is proposed to 

 describe in future issues the instrumental equip- 

 ment of the Bureau and the metrological work 

 undertaken there. A good portrait is given of Dr. 

 Guillaume, the director of the Bureau, who is to 

 deliver the Guthrie lecture to the Physical Society 

 to-morrow, April 23. In an article on the metric 

 system it is urged that, in addition to teaching the 

 system in schools, the Government should set a lead 

 bv adopting it in Departments such as the Post 

 Office, the Ministry of Health, and the Royal Air 

 Force, thus familiarising the public with metric 

 measures and preparing the way for a change which 

 is inevitable. Another feature of the number is an 

 explanation of the advantages of decimal coinage. 



A SUMMARY of the weather for the year 1919 has 

 recently been issued by the Meteorological Office. It 

 deals very fully with the annual results of the several 

 elements for numerous representative stations for the 

 several districts of the British Isles. The year was 

 generally dry, and was noteworthy for tjie heavy 

 snowstorm on April 27-28, and for the exceptionally 

 cold March and November. October, which is 

 normally the wettest month of the year, was in 

 rriany places the . driest. The mean temperature for 

 the year was below the normal in all districts, the 

 deficiency ranging from i-6° F. in East Scotland to 

 04° F. in the south of Ireland. The earth tempera- 

 tures were also below the normal, both at i ft. and 

 4 ft. below the surface. Rainfall was in excess in the 

 eastern districts and deficient in the western districts. 

 Sunshine was mostly in excess of the normal except 

 in some of the eastern districts. Data are given 

 showing the warmest day and warmest night, also 

 the coldest day and coldest night, for the several 

 stations of the different districts, and there are 

 similar details for the several months. Monthly 

 frequencies of sunshine for selected stations are 

 shown. Days in the year with rainfall between fixed 

 limits are given for selected stations, and the 

 number of days in the year with certain maximum 

 and minimum temperatures. Many and various 

 particulars of anemograph observations- are given, 

 with the frequency of hours with average wind 

 speed, also with a maximum hourly speed. A table 

 shows the frequency of winds of various strengths 

 from different directions for several stations in different 

 parts of the British Isles. Much of the data is in 

 a form which will be available for aviation require- 

 ments. 



The February and March issues of the Journal of 

 the Franklin Institute contain the report of the com- 

 mittee — consisting of Messrs. E. P. Hyde, P. W. 

 Cobb, H. M. Johnson, and W. Weniger — of the Nela 

 Research Laboratory which undertook the investiga- 

 tion of the relative merits of monocular and binocular 

 field-glasses under Service conditions. The tests ^re 

 npt yet completed, tut already afford a large arnount 

 Qf valuable inforrnation. The principal conclusions of 

 Ae eighty pages of the report are that in the hands 

 NO. 2634, VOL. 105] 



of not very experienced observers the monocular 

 requires to have a magnification of 6-27 in order to 

 give the same results as a binocular of the usual 

 magnification of 6-o. As regards rapidity of produc- 

 tion and adjustment, cost, weight, portability, and 

 ease in use the monocular is far ahead of the 

 binocular. The report deserves careful •onsideration 

 by optical-instrument makers in this country. 



In an article in the April issue of Science Progress 

 Major A. E. Oxley summarises his work on ' the 

 magnetic properties of about forty organic compounds 

 between -180° and 200° C, and shows that atomic 

 theories of the Rutherford-Bohr type, which negkct 

 magnetic forces, are incapable of accounting for 

 many of the magnetic properties of matter. How 

 these theories are to be modified he is not yet in a 

 position to say, but his diagram of two atoms held 

 together by electromagnetic forces shows these foi^ces 

 to be due to a pair of oppositely directed' circular 

 currents in each atom outside the positive nucleus and 

 rotating electrons. This idea is on the same lines as 

 those put forward recently by Parsons; (1915} and 

 Langmuir (1919). The author points out finally that 

 an adequate theory must account for the molecular 

 structure of crystals, and, the relations betwteenr that 

 structure and their behaviour in the magnetic field 

 must agree with stereochemistry, give the additive 

 property of diamagnetics, and show no dielectric 

 hysteresis. It is to be hoped that the forthcoming 

 discussion on the subject of atomic structure lat the 

 Royal Society will throw some light on these diffifcul>- 

 ties of present theories. , ' -• -'.In-. 



An important paper on the magnetic characteristics 

 of the iron core of a transformer or of an Induction coti 

 by the late Prof. B. Osgood Peirce is published in'^^ie 

 Proceedings of the American Academy of Arts' and 

 Sciences (vol. 1., No. 7, p. 149). ^ix'ty years' ''ago 

 Helmholtz verified the predictions of the mathematical, 

 theory of a transformer. Tlie verification, hdwevef, 

 was limited to the case when the inductances of' tfie 

 two coils were constant. With an iron core — We 

 case considered by the author — this assumption, 'is 

 not justified. He first tried the loading' Coil's 

 which are used in long-distance telephony. 'The cores 

 of these coils are made of iron wire only otie-teilth' df 

 a millimetre in diameter. The eddy currents induced 

 in the core are therefore negligibly small. Assumahg 

 merely the connection between the ampere-turns,; and 

 the magnetisation and Faraday's law for the electro- 

 motive force induced by a change in the^ ntagnertiid 

 induction. Prof. Peirce found that the experimental 

 results agreed with those deduced from theory to within 

 about the tenth part of i per cent., i.e. to within the 

 limits of experimental error. Even with the 6rdinary 

 closed iron circuit commercial transformer he: found 

 that the predictions of theory were verified > to high 

 accuracy when the eddy currents in the core could be 

 neglected. • It was concluded that a good approxima- 

 tion to the shape' of the current curves, .to the. rate 

 of growth of the excitation, and to the , flux, of the 

 i rqagnetic inductipn. in the core, of .^ transformer q^n 

 be obtained when an accurate static^ .hysteresis 

 diagram of the core over the given range is, ayail^ble. 



