672 



NATURE 



[August 28, 191, 



The third, or generalised type, is characteristic of 

 the great majority of desert plants; the prevalent idea 

 that the roots of such plants are usually very long has 

 no adequate foundation. The author adds interesting 

 notes on the environment of the roots of desert plants 

 — height of water-table in the soil, soil temperature, 

 soil air, &c. — and indicates the problems which are 

 being investigated at the Desert Laboratory with 

 regard to the relation between desert plants and the 

 soil. 



The relative value of strong and weak wheats is a 

 controversial question which has more than once 

 engaged attention in the columns of Nature. The 

 former type of wheat yields flour which is preferred 

 by the professional baker in large cities for a number 

 of reasons, and therefore commands a higher price. 

 It has come to be considered of higher quality, and it 

 is at present the object of wheat breeders all the world 

 over to convert the indigenous weak wheats into 

 stronger varieties. It is generally stated (for example, 

 Humphries, Royal Society of Arts, 1900, 239) that the 

 wheats which yield flour better suited for British con- 

 sumption (bv which the manufacturing centres and 

 towns are implied), do not suit the native Indian 

 requirements so well ; indeed, wheat is more often 

 consumed bv the natives in the form of coarse cakes 

 toasted by the side of an open fire than in the form of 

 the light, well-risen loaf known to us. However, Mr. 

 and Mrs. Howard, whose work in improving Indian 

 wheats is receiving wide recognition (see Nature for 

 August 7, p. 586), write to say that they do not agree 

 with this view of the question, and they claim that 

 the class of wheat preferred by the people of India 

 for their own food is the same as that in greatest 

 demand in the English markets. Mr. and Mrs. 

 Howard realise fully (Agric. Journal of India, Hi., 

 p. 31) that any improvement in the quality of wheat 

 to be of importance must satisfy both the people of 

 India and the home millers. 



The cultivation of tobacco in the Nyasaland Pro- 

 tectorate would appear to be full of promise, if one 

 may judge from the report of the director of agricul- 

 ture for the past year. During the period 2 1 2 



the total export of tobacco has increased from 60 lb. 

 to 2} million -lb., and the locally grown material so 

 strongly resembles Virginian-grown tobacco that it 

 is readily absorbed by the trade. In view of the large 

 grants which have been made from the Treasury 

 towards the cultivation of small quantities of inferior 

 tobacco in Ireland, it is certainly striking that so 

 much progress has been made in Nyasaland, even 

 without the assistance of a tobacco expert. The 

 claim is made that the possibilities of the Protectorate 

 for tobacco-growing are probably greater than those 

 of any other part of the British Empire. 



A useful note on "Thunderstorm Statistics of 

 Egypt " is contributed by Mr. E. W. Bliss to The 

 Cairo Scientific Journal for June. The data are sum- 

 marised from a list of all available records of storms 

 prepared by request of the Cairo Department of 

 Ordnance by the Meteorological Service, and refer 

 chiefly to observations at Abbasia between 1868 and 

 1912. A table including both slight and severe storms, 

 and also many cases where only lightning was ob- 

 NO. 2287, VOL. 91] 



served, shows that during the above period electrical 

 discharges were experienced on 1S0 days only. Cases 

 occurred in each month except July, the majority 

 being in October and November, and their rarity bears 

 out a statement previously made that in Egypt 

 thunderstorms are comparatively few in number. 

 Storms accompanied by hail or heavy rain, or which 

 did damage to buildings, only amounted to twenty- 

 eight in the forty-five years, an average of rather 

 more than one in two years. The discharges appear 

 to occur most frequently during the evening hours. 



The Canadian Department of the Naval Service, 

 Ottawa, has issued a useful pamphlet on "The cur- 

 rents in the entrance to the St. Lawrence," from 

 investigations of the tidal and current survey in the 

 seasons of 1895, 191 1, and 1912. The most modern 

 methods were employed in the investigation ; the tem- 

 perature and density of the water, and complete 

 meteorological observations were also taken. Between 

 the Gaspe coast and Anticosti the currents present a 

 complete contrast in their behaviour ; on the one shore 

 there is a current flowing always in the same direc- 

 tion, while on the other the set is weak and con- 

 tinually veering. One of the chief endeavours has 

 been to reduce these currents to law, and in the case 

 of the Gaspe current it has been largely successful. 

 Although the veering currents are weak, and at times 

 irregular, it has been possible to prove that the tide 

 has a dominating influence upon them, and that their 

 directions during flood and ebb are fairly definite as a 

 rule. The features of both currents are discussed in 

 considerable detail. 



The July number of Hinuncl und Erde contains the 

 address delivered by Dr. M. Laue on taking up his 

 professorship at Zurich in December last. Naturally, 

 it deals with the new field of research opened up by 

 his own experiments on the reflection of Rontgen 

 rays by crystals. From the results obtained by him- 

 self, a*nd by others who have repeated his experi- 

 ments, he concludes that the wave theory of the 

 constitution of Rontgen rays is in much closer accord 

 with the facts than the form of emission theory advo- 

 cated by Prof. Bragg. The difficulties in the way of 

 its general acceptance are not greater than those with 

 which the wave theory of light has to deal, and the 

 rejection of the wave theory in one case would necessi- 

 tate its equaj rejection in the other. 



In a paper read before the American Institute of 

 Electrical Engineers in March last, Mr. C. Fortescue 

 showed how the excessive concentration of electrical 

 stress which is to be found at certain parts of the 

 insulation of electrical apparatus could be replaced 

 by a uniform stress of much smaller amount. A 

 short account of the electrostatic theories which 

 underlie Mr. Fortescue's method is given by Prof. 

 W. S. Franklin, of Lehigh University, in the July 

 number of the Journal of the Franklin Institute. 

 Prof. Franklin shows that the two propositions — an 

 equipotential surface may be to any extent replaced 

 by a thin metal sheet without disturbing the field, and 

 a closed metal shell screens its inside from outside 

 effects — form the basis for most of the devices sug- 

 gested. Taking the field round a charged wire or 



