64 



NA TURE 



[May 2 1, 1908 



and a half of woodland for every acre of arable land. 

 Within recent years the necessity for re-planting has been 

 recognised ; Crypiomeria japonica and other conifers are 

 «enerally selected, but camphor and chestnut trees are also 

 la. gelv planted; around the fields, mulberry, lacquer, and 

 vegetable-wax trees are grown. 



Mr. C. F. Str.awson has issued his ninth annual report 

 on the destruction of charlock in corn crops during 1907 

 bv spraying with a copper sulphate solution. Experiments 

 extending over ten years have shown that young charlock 

 can be destroyed in growing corn crops without injury to 

 ihe latter by spraying with fifty gallons of 3 per cent, 

 solution of copper sulphate (15 lb. to fifty gallons) per 

 statute acre, and older charlock with a stronger solution. 

 The corn crops are much improved, :i id give a better 

 vield, where the charlock is des-'oved, and young grass 

 seeds and clover in the corn remain uninjured. The object 

 of Mr. .Strawson's annual reports is chiefly to induce those 

 who cultivate charlock-seeded soils to adopt this new and 

 easy method of restoring the land to its full crop-producing 

 value. 



In a paper read before the Physiological Society on 

 March 21, Dr. A. D. Waller, F.R.S., demonstrated that 

 the contractility of animal and vegetal nerves observed by 

 Prof. Bose (see Nature, March 5, supplement, p. iii) 

 mav be obtained on fiddle-strings, or any other kind 

 of strings, and is due to heating of the structures by the 

 " fairlv strong tetanisation " curi'ents used by Prof. Bose. 

 Dr. Waller calculates that the heat developed by the 

 currents used, in the absence of evaporation, is sufficient to 

 raise the temperature of a nerve t°-3S per sec. Engelmann 

 in 1895 showed that fiddle-strings in water contracted when 

 heated. With weak tetanisation there is obtained elonga- 

 tion, with strong, shortening. The weight and the electrical 

 conductivity of a fully contracted string are greatly 

 diminished by loss of water. 



O.NE of the most important agricultural questions in 

 Cape Colony, the deterioration of the veld, is discussed in 

 the March number of the Agrictiltural Journal of the Cape 

 of Good Hope. It seems to be established that the veld 

 will no longer nourish cattle as well as formerly, and five 

 causes are stated to have brought this about : — (i) over- 

 stocking and the kraaling of stock ; (2) formation of sluits 

 or dongas ; (3) spread of noxious weeds ; (4) burning of 

 the veld ; (5) destruction by drift sands. Overstocking, 

 i.f. putting too many cattle on to a given area, is harmful, 

 because the grasses or plants relished by the animals are 

 so completely eaten off that they become exterminated, and 

 their place is taken by plants which the animals have 

 rejected, and which are, therefore, of no agricultural value. 

 Some are positively noxious, e.g. the jointed cactus 

 {Opimtia pusilla), which is likely to cause considerable 

 trouble in future, the prickly pear, and the Mexican poppy. 

 Kraaling, or herding the animals together at night to 

 protect them from jackals, &c., has the effect of wearing 

 down definite pathways, and thus starting the channels 

 for the flow of water which finally develop into the sluits 

 and dongas so characteristic of the veld. The burning of 

 the veld is responsible for a good deal of damage, since 

 the organic matter is largely destroyed, and there is con- 

 siderable loss of nitrogen. Nevertheless, some means of 

 removing old dead grass is necessary, for a good deal is 

 apt to be left over from the previous season ; sheep will 

 not eat it, and it interferes with the new growth ; there 

 seems no option but to burn it. The 'whole problem is of 

 vital importance, and can only be solved after careful 

 scientific investigation. 



NO. 2012, VOL. 78] 



The American Government, in view of the rapid occupa- 

 tion of all the available land in the western States, has 

 started a vast reclamation scheme. The most important 

 is that for the irrigation of what are known as the Great 

 Plains, the region extending from the Missouri River to 

 the foot of the Rocky Mountains and from the Panhandle 

 of Texas northward to the Canadian frontier. The pro- 

 jects now sanctioned in various parts of the country 

 provide for the expenditure up to the year igii of about 

 fourteen millions in the reclamation of some two millions 

 of acres. The progress of this great experiment is de- 

 scribed in the April number of the National Geographical 

 Magazine by Mr. C. J. Blanchard, statistician to the 

 U.S. Reclamation Service, under the title of " Home- 

 making by the Government." The illustrations of fruit 

 and other products grown under irrigation present a vivid 

 picture of the possibilities of this important enterprise. 

 The most remarkable of these projects is the Salt River 

 scheme in Arizona, which involved the construction of the 

 " most wonderful highway ever built by man," that on 

 Fish Creek Hill, where a road has been cut along the 

 banks of a stupendous canyon through the living rock for 

 a distance of forty miles. 



The chain has hitherto received scant attention from 

 investigators in the field of elasticity and strength of 

 materials, and a welcome addition to the two or three 

 scattered memoirs on the theory of the stresses in chain- 

 links is made by a memoir on the strength of chain-links 

 by Prof. G. A. Goodenough and Prof. L. E. Moore, form- 

 ing Bulletin No. 18 of the University of Illinois Engineer- 

 ing Experiment Station. The investigation described 

 deals with the development of the theory of the stresses in- 

 duced in chain-links with given conditions as regards load- 

 ing, with experimental tests of the validity of the theory 

 employed, and with the assumptions made as to the distri- 

 bution of pressure between adjacent links, and the deduction 

 from theoretical considerations alone of rational formulae 

 for the loading of chains. Experiments made on steel 

 rings were found to confirm the theoretical analysis 

 employed in the calculation of stresses. E.xperiments on 

 various chain-links further confirm this analysis. The 

 introduction of a stud in the link equalises the stresses 

 throughout the link, reduces the maximum tensile stresses 

 about 20 per cent., and reduces the excessive compressive 

 stress at the end of the link about 50 per cent. The 

 following formula are applicable to chains of the usual 

 form : — P = o-4 (PS for open links, and P = o-5 d'S for stud 

 links, where P denotes the safe load, d the diameter of 

 the stock, and S the maximum permissible tensile stress. 



The report of the Meteorological Service of Canada for 

 the year 1905 has recentiv come to hand ; it consists of 

 xix-l-418 quarto pages, nearly all of which are taken up 

 with monthly and annual summaries, including hourly or 

 bi-hourly observations of air-pressure and temperature at 

 some of the first-order stations. The careful preparation 

 of these voluminous tables is of itself a stupendous under- 

 taking ; among the e.xtreme shade temperatures we note 

 I04°.5 at Spence's Bridge (British Columbia) in July, and 

 — 53°.o at two stations in Alberta in February. The per- 

 centage of fulfilment of weather forecasts is very satis- 

 factory, the average for all districts being 85- 1 ; the greatest 

 annual success is 86-9, in the Upper St. Lawrence district. 

 In an interesting supplement Prof. W. J . Loudon discusses 

 the effect of difTerent winds on the " seiches " observed, 

 and also gives the results of his researches in atmospheric 

 electricity, at High Rock station, Georgian Bay. 



In the Physikalische Zeitschrift for May i Dr. L. 

 Mandelstani considers the question whether the usual 



