6o2 



NA TURE 



[October 20, 1923 



as the mathcmatirians ;\\\<\ tihvsicists had antici- 

 pated ; from till- 1110(1(1 '-construct 

 the method l'\ ulii(li tin 1 after cell 

 (li\ isii 111. 



■ K'l II I'l \Ni " IN Strawhkkkiks. — During recent 

 yen tin in.iid of a mysterious disease among 

 StTaubcnus has been reportnl under this name from 

 one centre of strawberry r aiiotlicr, in 



some districts the straw!" i !n tr\ Ix-ing 



8eriousl\- t hrratfiicl li\- it> . li-|.i ii l.i 1 1. :'ically 



diseased iilant-, lia\r liccii iiiKlff (il)N(: ,,t: the 



Rcscan h StalHMi, I.'iiil; Aslitdii, i'.riilnl, and now 

 Messrs. 1',. ilallard and (1. S. I'lTcn report, that the 

 disease is only a special form of the well-known 

 " cauliflower " disease of strawberries \vlii( h has been 

 known for some thirty years and was ti 'd 



by Mrs ( )rincrod. As in the case <■ i 



flower " tlisease, the causal organism in red pianr 

 is found to be the eelworm Aphelenchus fragario 

 Ritz. Bos, a conclusion which, as recent correspond- 

 ence in the Gardeners' Chronicle witnesses, is in agree- 

 ment with that of other practical observers familiar 

 with the disease. " Red plant " appears to be an 

 unfortunate name for the disease, as it is only when 

 the eelworm attack synchronises with a certain stage 

 of development in some varieties of strawberry that 

 the striking red colour develops in the petiole and 

 lamina of the ill-developed leaves. 



Control of Finger-and-toe by Liming. — In 

 Bull. No. 29 of the North of Scotland College of 

 Agriculture, Prof. Hendrick describes an experiment 

 carried on for several years at Craibstone under 

 conditions particularly conducive to the spread of 

 finger-and-toe disease. The soil is sour and very 

 poor in quality, and turnips have been grown on 

 the same land since 191 5 ; mass infection has been 

 induced by leaving plenty of diseased material upon 

 the plots, and manures favourable to the increase 

 of the disease have been systematically applied. 

 Although disease occurs yearly on the limed plots 

 as well as on the unlimed, in the former case a large 

 proportion of the roots are fit for use, even though 

 touched by disease, whereas in the latter case most 

 of the roots are rotten and unusable. It would 

 seem that though a cure is not effected, some measure 

 of control can be exercised by adequate applications 

 of lime, in moderate excess, but in each individual 

 case it will be necessary to balance the cost of the 

 liming against the improved value of the crop, in 

 order to determine whether the procedure is economic 

 and advisable. 



Inaudible Air-waves. — The current number of 

 Science Progress (pp. 294-297) contains an article by 

 Dr. C. Davison on inaudible air-waves resulting from 

 explosions. These waves are manifested chiefly by 

 the rattling of windows, the disturbance of pheasants, 

 and the traces of barographs. Such effects are 

 noticed far beyond the area within which the sound 

 of the explosion is audible. For example, the firing 

 during the Dogger Bank action of January 24, 1915, 

 was heard in England to a distance of 208 miles, 

 while pheasants were disturbed near Workington 

 (320 miles). The velocity of the inaudible air- waves 

 is slightly less than that of sound, but, when a silent 

 zone is developed, the sound-waves, which at first 

 outrun the inaudible waves, in the outer sound-area 

 follow them after a brief interval. As windows are 

 shaken and pheasants are disturbed in the silent 

 zone, it is suggested that the inaudible air-waves 

 cross the silent zone close to the ground while the 

 sound-waves travel at a somewhat greater elevation. 



Industrial Water Supply in the United 

 States. — An inquiry into the nature and source of 



the water used in ind'-';''^;-'' ..^« >>a..i...,^nts in th.- 

 United States has hi ,,1,, results 



These are published n ....,.,.., . ujK'r No. ^','> 



of the United ol'.gical Survey. The censu, 



of 1020 showe -• per cent, of the total ooi, i 



jatioi: pi u es eaeli of morc than 



"ihah. \ ses of the water supply o: 



287 places and, 111 addition, of many smaller pla 

 given so that each state is represented by at 1« , 

 cities. These details deal with the bulk of the wai- ■ 

 used for industrial pnrpr>sf^s even if they show ih 

 character of the wa t 1 )y less than half the tota ! 



population. Man\ analyses are the work of 



the Geological Survc) ; others have been ol. 

 from municipal, state, waterworks, and com 

 laboratories. Of the 307 cities quoted in the • ; • 

 the great maj(jrity has surface water but a feu iia\e 

 ground water. A sk-trh map shows the average 

 distril)iition of hardiie-,^ Ihis quality, due to calcium 

 and inai^iicsiuni .salts, i.s practically the only one of 

 niiK h ill lustrial importance. Thefigures show that 

 of the ^9,000,000 persons served with the waters 

 analyst d, about 17,000,000 use water with less than 

 55 parts per million of hardness, 6,000,000 use water 

 with 55 to ir. iiillion, and most of the 



remainder use o to 200 parts of hardness 



per million. Tlie paniplilet contains also a discussion 

 of the treatment of water for public supplies. 



The Determination of S ; .^In an article 



in Science Progress for Octoliei on the levels of land 

 and sea. Sir Charles Close di-scusses the problem of 

 arriving at the mean level of the sea as the datum to 

 which height on the Ordnance Survey maps of Great 

 Britain are referred. What is required is the mean 

 position of the sea surface as determined over a con- 

 siderable period of time, at all states of the tide, and 

 not merely at high and low water. The most satis- 

 factory way of arriving at this mean is by the use of 

 self-recording tide-gauges. In practice the mean of 

 the hourly tides measured over a long period will 

 give the result desired. For this purpose tidal 

 stations were set up at Dunbar in 1913, Newlyn in 

 1915, and Felixstowe in 1917, and are still at ^orET 

 Each of the two stations of longest duration show a 

 range in height of the annual mean sea-level of 2-3 

 inches. Hence it is obvious that the value of mean 

 sea-level cannot be obtained during the period of a 

 year. At other stations in the British Isles and else- 

 where, annual fluctuations have been noted. In fact 

 the probable variation of height of any one year 

 from the mean of a large number of years is about 

 half an inch. The most important variations are 

 meteorological and are in part local, in part world- 

 wide. Of smaller significance are the latitude varia- 

 tion tide with a period of 431 days and the lunar 

 tides of 1 8-6 years. 



SuNSPOTS and Air Temperaturi: in America. — 

 The Monthly Weather Review for May contains an 

 article on sunspots and terrestrial temperature in the 

 United States based upon a communication to the 

 American Meteorological Society by Mr. A. J. Henry 

 of the U.S. Weather Bureau. It is pointed out that 

 annual deviations of temperature give evidence of 

 short period variations within the 11 -year sunspot 

 cycle. Sometimes warm and cold years alternate ; in 

 other cases the cycle, cold to warm, would be completed 

 in three, four, or five years. During the period 1870- 

 192 1, a heat maximum corresponds fairly well with 

 a maximum of sunspots and vice versa. Prior to that 

 period the agreement is not so good. The author 

 mentions that until some allowance can be satis- 

 factorily made for the movement of cyclones and 

 anticyclones, it is hopeless to seek for effects of changes 



NO. 2816, VOL. 112] 



