5IO 



NATURE 



[February 28, 191; 



W. R. Cooper; Librarian, Dr. S. W. J. Smith; Other 

 Members of Council, Prof. E. H. Barton, Mr. C. R. 

 Darling, Prof. G. W. O. Howe, Dr. D. Owen, Mr. 

 C. C. Paterson, Mr. C. E. S. Phillips, Dr. S. Russ, 

 Mr. T. Smith, and Mr. F. J. W. Whipple. 



Mr. H. G. Beasley describes, in the February issue 

 of Man, a remarkable form of wooden hook, known 

 as Matau Hokori, from Greenwich Atoll, the greatest 

 length o* which is 7I in. It is the crudest specimen 

 hitherto received from the Pacific, fornied from a 

 natural root of a pale-coloured wood, of light weight. 

 The maker scarcely troubled even to remove the 

 notches, and in many places has left the bark intact. 

 The barb is of similar wood, and shows a certain 

 amount of skill in the way it is scarfed to the shank ; 

 it was apparently finished with some blunt implement 

 and afterwards with a rasp. The hook is a poor 

 sipecimen of Polynesian art, but this is not surprising 

 considering the remoteness of this little group of islands 

 and the smallness of the population. 



"Reconstruction and Public Health" is the subject 

 of an article by Mr. E. J. Lidbetter in the Eugenics 

 Review for January (vol. ix.. No. 4). Mr. Lidbetter 

 points out that public health administration has 

 hitherto been based upon prevention in the economic 

 sense, and is not concerned with the individual, who 

 is dealt with under the Poor Law. He pleads for co- 

 ordination between the public health service and organ- 

 isations for the treatment of individual sickness, e.g. 

 the hospitals, and the divorce of Poor Law administra- 

 tion in the treatment of the sick independent members 

 of the community. 



In the November issue of the Journal of the 

 Quekett Microscopical Club (vol. xiii.. No. 81) Mr. 

 W. M. Bale describes a method for the measurement of 

 magnifying powers. The method is as follows : — 

 Measure the exact diameter of the magnified field pro- 

 jected with a camera lucida or Beale reflector at a 

 distance of 10 in. Measure also with the stage micro- 

 meter the actual diameter of the field. Then the first 

 figure divided by the second gives the magnifying 

 power. But a small correction has to be made, be- 

 cause in the camera image the magnification is appre- 

 ciably greater at the marginal portions of the field than 

 near the centre. This varies from i mm. with a 

 4-in. field (loi mm.) to 9 mm. forag-in. field (203 mm.)» 

 being at the rate of i mm. for every J-in. increase in 

 the diameter of the field. Mr. Maurice Ainslie gives 

 some further notes on this method, and describes an 

 alternative method by the measurement of the Rams- 

 den disc. 



The annual report on the Agricultural Department, 

 St. Vincent, for the year ended March 31, 1917, con- 

 tains a further account of the work being done to con- 

 trol the ravages of the cotton-stainer {Dysdercus delau- 

 neyi, Leth.), which is so serious a pest of cultivated 

 cotton in this island and elsewhere in the West Indies. 

 The life-history of the insect has been carefully studied, 

 and it has been found that 'the eggs are deposited in 

 masses in th^ ground and carefully covered over, where 

 they take seven and a half to nine days to hatch. 

 Destruction of eggs in the field unfortunately does not 

 appear to be practicable, and the campaign against the 

 insect has to take the form of destruction of its native 

 food plants. A special Ordinance has been passed, and 

 between August, 1916, and April, 1917, 1542 silk cotton 

 trees (Eriodendron anfractnosum), 11,570 "John Bull" 

 trees (Thespesia populnea), and several thousand seed- 

 lings have been destroyed. Collection of insects, etc., 

 is also suggested among other measures, as the insect 

 has no natural enemy of importance. 

 NO. 2522, VOL. 100] 



The question of the precise fertilising value of the 

 basic slags' of low solubility which are commonly ob- 

 tained in the manufacture of steel by the basic open- 

 hearth process has attracted considerable attention 

 during the past few years. The annual production of 

 such slags has been recently computed at 750,000 tons, 

 and with the projected extension of the iron and steel 

 industry this output will steadily increase. The low solu- 

 bility of the phosphate in these slags is partly attribut- 

 able to the use of fluorspar in the manufacture, and there 

 is some reason to think that the conventional method 

 of assessing the solubility of slags by means of weak 

 citric acid solution is liable to lead to an undervalua- 

 tion of their merits in comparison with the more highly 

 soluble slags obtained in the Bessemer process. This 

 view apparently receives considerable support from the 

 results of field trials in Essex, the results of which are 

 contributed by Mr. G. S. Robertson to the January 

 issue of the 'Journal of the Board of Agriculture. At 

 each of three experimental centres in the two years of 

 experiment the hay crops obtained with the fluorspar 

 slags compared very favourably with those obtained by 

 the application of the same weight of phosphoric acid 

 (200 lb. P2O5 per acre) in the form of slag of high 

 solubility. Results almost as good were also obtained 

 with equivalent dressings of ground mineral (Gafsa) 

 phosphate. At one centre, however, other plots were 

 added on which the phosphates were applied at one- 

 half the above rate, and the fact that the yields on 

 these plots were fully equal to those obtained with the 

 heavier applications suggests that the latter were too 

 heavy to furnish a decisive test of the citric solubility 

 criterion. It is noteworthy, however, that with the 

 lighter application the fluorspar slag showed a distinct 

 advantage over the more highly soluble slag. 



The Summary Report of the Geological Survey of 

 Canada for 1916 (Ottawa, 1917), a volume of 420 pages, 

 records good war service on the part of the staff, both 

 in the forces in Europe and in the ever-widening field 

 of mineral discovery. Tungsten ores, especially 

 scheelite, are recorded from alluvial deposits on granite 

 in the Yukon plateau, where the climate prevents the 

 concentrates that are secured in one summer from 

 being available until the following winter— that is, until 

 they can be removed on sleighs. A similarly interest- 

 ing touch is given to operations on the tungsten ores 

 (wt)lfram and scheelite) of New Brunswick, when it is 

 stated that a mill cannot be remodelled until* snow 

 makes haulage of material practicable. Magnesite 

 attracts attention in British Columbia (Bridge River 

 district), where it occurs, with separable veins of chal- 

 cedony, in serpentine. The Arctic expedition organised 

 by the Survey reports an extensive copper region on 

 Bathurst inlet. In Banks Peninsula native copper 

 occurs amygdaloidally throughout lavas- 350 ft. in 

 thickness. 



It is known from the work of Prof. Barkla that the 

 scattering of ordinary X-rays by light elements agrees 

 well with the view that the number of scattering elec- 

 trons in an atom is about equal to the atomic number 

 of the element as given by Moseley, and that each 

 electron acts as an independent radiating centre; the 

 scattering of the penetrating y rays of much shorter 

 wave-length is, however, markedly less than the value 

 to be expected on the simple theory, and the scattered 

 radiation is mostly in the direction of the incident rays. 

 In a recent paper Mr. A. H. Compton (Journ. Wash. 

 Acad. Sci., January 4) attacks this problem from a 

 new point of view. He supposes that the simple theory 

 of scattering no longer holds when the wave-length is 

 comparable with the linear dimensions of the electron. 

 For purposes of calculation he takes the electron to 

 consist of. a sphere of positive electricity, each part of 



