August 22, 1918] 



NATURE 



495 



TREATMENT OF CROPS BY ELECTRIC 

 DISCHARGES. 



PROF. HENDRICK has described in the Scottish 

 Journal of Agriculture (vol. i., 1918, pp. 41-51) 

 the results of some extensive experiments on the treat- 

 ment of grovi-ing crops v^^ith an overhead electric dis- 

 charge. The work was carried out during the years 

 1913, 1914, 1916, and 1917 on Mr. Low's farm of 

 Mains of Luther, Kincardineshire. The apparatus 

 was that of the Agricultural Electric Discharge Co., 

 Ltd., consisting of an interrupter, induction coil, and 

 Lodge valves. The overhead installation consisted of 

 a number of fine wires (the diameter is not stated) 

 arranged 15 ft. apart, and alternately bare and cotton- 

 covered; these wires were about 11 ft. from the 

 ground at the centre and 15 ft. near the supports. 

 The experimental area consisted of ten plots, each 

 0-56 acre, half of each plot being electrified and half 

 used as a control ; the control areas lay south-east 

 of the electrified ones. In -1914 a galvanised-wire 

 netting (5-in. mesh) was placed between the electrified 

 and control areas. . A five-course rotation was fol- 

 lowed (turnips, barley, hay, potatoes, and oats), and 

 the ten plots were so arranged that "in each season 

 '■ two whole plots were under each of the crops of 

 the rotation." In 1917 the treated barley showed 

 an increase in grain of 31 per cent, over the control, 

 but this result was not obtained in other years, and 

 the general conclusion is arrived at that no persistent 

 improvement was obtained in any of the crops grown. 

 These careful experiments show clearly the neces- 

 sity for caution in this type of work, but, unfor- 

 tunatelv, thev do not advance our knowledge of the 

 subject. In investigations on electro-culture there are 

 two main aspects, the agricultural and the elec- 

 trical ; in these experiments, however, while the 

 agricultural conditions have been carefully considered, 

 the electrical conditions have been treated with com- 

 parative neglect. The information is given that the 

 apparatus was capable of giving a current at 60,000 

 to 100,000 volts, but no measurements appear to have 

 been taken of the actual voltage employed or of the 

 discharge current from the wires, and no data are 

 given as to the number of hours, or the time of day, 

 during which the discharge was employed. The 

 experiments were certaiplv a failure, but we bannot 

 say under what electrical conditions the failure . oc- 

 curred. It is thus impossible to repeat the experi- 

 ments or to compare them with experiments in which 

 more successful results have been claimed. 



IRON-ORE OCCURRENCES IN CANADA. 



THE Canadian Department of Mines has just 

 issued the second (final) volume of a report 

 upon iron-ore occurrences in Canada by Messrs. E. 

 Lindeman and L. L. Bolton. The first volume con- 

 tains an account of the principal operating mines that 

 may be considered active producers of iron-ore, and 

 the second volume gives brief descriptions of a very 

 large number of occurrences, some of which have 

 been worked in the past, but are not now contri- 

 buting to the output, whilst others have not been 

 attacked. A considerable number of more detailed 

 memoirs, such as those on the iron-ore deposits of 

 Nova Scotia, on the Wabana iron-ore of Newfound- 

 land, etc., have already been published by the Depart- 

 ment of Mines, but the present work is particularly 

 useful, as it not only summarises these, but also 

 describes a verv large number of occurrences about 

 which no information has hitherto been available. 

 .\ very useful feature, too, is -the very complete series 



NO. 2547, VOL. lOl] 



of references to any previously published descriptions 

 of the mines or occurrences. . Another, to which atten- 

 tion may with advantage be directed, is the large 

 number of magnetometric maps that accompany the 

 present report. It is pointed out in the introduction 

 that particular attention has been devoted to these 

 magnetometric methods, which have hitherto been but 

 rarely employed outside Scandinavia, where they 

 originated, because it is desired to impress the value 

 of this method of working upon Canadian -mining 

 engineers, since definite information can thus be ob- 

 tained as to the size, shape, and distribution of 

 deposits of magnetite, while magnetometrv pro- 

 vides a permanent record that will serve as a guide 

 in the further exploration or development of these 

 deposits. 



BRITISH SCIENTIFIC PRODUCTS EXHI- 

 BITION. 



'TPHE British Science Guild has carried out success- 

 -*■ fully a very useful enterprise in the British 

 Scientific Products Exhibition, which was opened by 

 Lord Sydenham, president of the Guild, on August 14, 

 at King's College, London. The exhibition contains 

 many examples of products and appliances of scientific 

 and industrial interest which, prior to the war, were 

 obtained chiefly from enemy couritries, but which are 

 now produced in the United Kingdom. It is an im- 

 pressive reminder to all of the great advance made in 

 the production of articles of prime importance 

 for the home and foreign markets hitherto ob- 

 tained from other countries. The exhibits cover 

 a wide range, and include chemical products 

 and processes, physical and electrical appliances, 

 optical apparatus, measuring and mechanical in- 

 struments, surgical, bacteriological, and pathological 

 appliances, including X-ray apparatus, etc. In prac- 

 tically all the sections the degree of progress indicated 

 by the exhibits is surprisingly great, and even where 

 no striking development has occurred in the wav of 

 new invention, there is noticeable a marked general 

 improvement in apparatus constructed on the recog- 

 nised lines of pre-war days. 



Interest naturally centres round those exhibits asso- 

 ciated v^-ith aircraft production. Here the developments 

 and the differences between present-day aeroplanes 

 and those of a few years ago are clearly marked. 

 Modern spars, for instance, are much stronger for a 

 given weight, engines have been developed as 

 regards both material and construction to the extent 

 of reducing their weight by more than one-half, whilst 

 the size and power have grown enormouslv and are 

 still making advances. The metallic materials which 

 have been produced since the outbreak of the war, 

 and of which aircraft constructors have been able to 

 avail themselves, have made it possible for the greater 

 part of an aero-engine to be made of light alloys. 

 In non-metallic materials the investigation of timber 

 has led to some interesting results. With regard to 

 the many fittings which go to make up the complete 

 aeroplane, one item of outstanding interest is the 

 magneto. Before the war the Germans had prac- 

 ticallv a monopoly in the manufacture of this article 

 for both car and aeroplane use, the Bosch magneto 

 undoubtedly being the most popular throughout the 

 world. The war has changed that, and the British 

 manufacturers have seen to it that the home-built 

 magnetos are worthy of their name. There are now 

 nine British firms engaged in this work, with the 

 result that during the past four years 300,000 magnetos 

 have been manufactured for war service alone. What 

 is equally important is that the home-made magneto is 



