500 



NATURE 



[June 8, 191 1 



<ii llii- w all r II'-. (1. 



, nfvcrthf- 



1. . m.iii'. ijiii .1 ii 1:1 "f poiiul.i 



i \-, ll ll lllli|l^l\ I- 1 nil l\ .U Hill li 



IIh- |)ii--il iciii iiik! ih.- i,.,,\'.cii. 

 \\ A\' I I.iImi- III 11m .i1Iu\ i:il plain n' ■ : 

 siiini' ))i fiiinmai V work in priAiou- 



iiivisl i^alioii wa^^ --(arli-d in I |.p' i > ;:m' .^-^^.l 



(aiio, in 111117 S, In (iliiaiii (lilinilr information. I hi-, 

 now lii-in pniili-ii'i! in iir foiiii of a (l<-pai t ni'iilal iiai>' 

 Mr. II. 1. I ■ . . :iral Sui'. 



( )l,sii \ :i! '..n , ..-lis wiiii i 



anil : 1' - -1.1. a .Ml a\.Ta-r ol ' '. 



ilui I iiioiillis h mil o;ir llooil of 111 



111,- 11. M : -MU. i;o i.i'ilfall OMlll^ lo ( oMIJllii air lif 101 

 (litions, lli<>.' (lala \\i II- Minirii-nl lo di lim- v.illi aili-t;ual' 

 acriirac \ llir laiav .mil inovi-m<-nI of ilii- w.-iO r-I.-iMi- in 

 thai \i-.-ir. Tin : oi k lioiiL.:h in wliii li tin- Xili How-, i.s 

 lar^i-h I'llli ll li\ p|. i-ior.-iii- s.iniN .uul ^i:i\i-K. o\-.-r wliiili 

 llii: allnvi.'il il'-posiK li.i\" 1)1 in laid down, .'md into lln-si- 

 ihi" widls fn>m uliii li w.id I'-wIin-l-i lift watrr ari- iisnalh' 

 diu; down tliroui.ili thr .■illuvinm .and inio tin- undi-rl\ ini.; 

 s.iiuN : Irom llii-vi- wi-lK niixt of lln^ ol)-~i.|-\-.it ions wrri- 

 lak'-n. \\ ni.iny poinis llii- \i|i> itsi-lf li.i-, rut into 

 ilii -M- --anih dihixial ili-po-,'is, or Hows ;i;4,-iinst ihcm .al tin- 

 maii^in ol ilii- \alli-\. --o Ilial llii- ri\<-r w,-ili-r is in com- 

 numiralion with holh di-po-^its. .\ srrii-s of (li;i<_;r.ims show 

 llii- v.irialion of ihr w.ilrr-|i-\-i-l in i-.-icIi wi-ll rhroii^-hoilt 

 ihr \rar, .and aUo ilii- position of llii> \\-;i|i-r-l;ililo for each 

 month ;it fiftn-n ditlVri nt |)oinIs of th,' ri\i-r. Slight diffi-r- 

 rnccs (lur lo \ .iri.it ions in piirosil\-, \-c., .-iri- to In- si-cn, hul 

 till- wholi' !^i\'i->- .a vi-r\- rli-ar ijiclurr of lln- inoviani'nl of 

 sulisoil wati-f. Till' lini-s fur ScptiMiihrr and Octoltrr show 

 its r.-ipii| ri-r, ;ift( r whirh ih'- fall rommi-nr.-s, li.-iiirr 

 L;iiali--t lii-|\\-i-i n ni-frnilii-r ;ind jaiui.arv and afti-rwards 

 d<-'rri-a--in;4. In ihi-si- lali-r months ihi-n- is of|i-n a slo]ii' 

 low.-irils till' ri\i-r, .•mil an apt'ri-i-i.iMi- amomil of stori-d 

 w.-ili-r is ihi-n n luriii-d from tin- llood |)l.ain lo the rivi-r. It 

 would havi' hi-i-ii pri-fi-r.'iblr if th<> ohsi-rvcd v.ihu-s liad 

 l)i-rn indirali-d on llu- di;iu;f.ams .and tin- dipths of llir wi-lls 

 dr.iwn, .IS till' rurvcs do not show to wli.at I'xli-nl thi-v .aro 

 ci.ntiolli d hv il.-il;i withou', frfi-ri-nr.> lo ihr printed t.ahlrs. 



In suhsri.].i(-nt rh.-,pti-rs .an .•iUcmpt is mado to cominilr 

 the iiu.aniitv of w.-iti-r whirh tin- alluvial plain can hold, 

 60 per ci-nt. hv volume hi-ini; t.-ika-n as tho water ahsorhed 

 hv the soil, hut m.-.i^uri-d discharsjos of the river and 

 1 .in;ils ;ire not utilis.-d, ;ind the vaUies ohtaitK'd cannot he 

 ri'i_;.-irdi-d .is niore th;in rou^h approxim.at 'ons. D.ala for 

 deicrmininii the dirr-clion of mo\-i'mi-iii ar.' sc;mtv; near the 

 river, roulls v.arv t;,-i';iilv within short dislances, and in 

 villa!.;"es ;inv use of colouriii!^ m.attor in such invest io;,| inns 

 would .arou-^e much hostilitv. A hir:,'e .amount of valunhle 

 dal.a h.'is 1,,-, n collected, which ^'n-allv increases our know- 

 ledo;!' nf the w.i(,-r in ihe Nile vnllev, and must he of the 

 i^retite^t v.ilue for agriculture and for puhlir health. 'I'lu- 

 welU nf the llood-plain .are t;rouped into those of the river 

 man^in which .-ire immedintelv affected hv its chancres of 

 le\-.-l, iho'.e of the pl;iin which h.ave ;\n annual rise and 

 hall ;i1'iuit a month .md .-i h.ilf after that of the river, and 

 those clo-.r' to the desi-rt mar^Ljin wlK-re the i-,-inc;e i> com- 

 n;ir.-it-\-i-lv small. J-'urilur !iivi-sii..nl ion on tho same line-; 

 has heen carried on since in the delt.a. whirh will bo puh- 

 lished in due course, formin;.^ a study of much value which, 

 it is to be hoped, will be continued in the future. 



THE ROY AT. (U;s /■: RVATOR V, GRFF.NWTCH. 



]^/| K. ^^•S(>^■•s th-st r-po • ^ ■: ■ , 



t"' ad ar ill:- .annual m- , , . : , , . , < 



held .at (.reenwich on June 2, and covers the \..ir . i.d. d 

 M.ay H). Below wi' erive a brief sunmiarv. 



_ The transit circle was employed for the usual oh- 

 tions and for tho observation of stars of inacnitu ' 

 and brifjhter between +24° and -f 32° north d. r, 

 The latter research, commenced in moti with th -■; 



of socurinjj five observations of e.ach star, inci 



12, 000 Stars, and about 48 per cent, of the obsi rvaiions 

 were completed at the date of report. 



From the transit-circle and altazimuth observations of 

 the moon's limb and Mostins^ A, made during looq. tho 



1 "The Movements of the Subsoil Water in Upper Egypt." lU- H. T. 

 rerrar. (Cairo: Survey Dept. Paper No. 19, igti.) 



Hjnd to b' 



■>m ninef, - 



111' 11 in;- i.-'ia^:! im> P'-'-n .-jiiii' 11 lo lll<- an.i/ 

 mild on iron r.iiU quite isolated from tli' 

 -■'■'iiiH~- .,1 111. -,:;,.■ imaii.-s Has bccomc i, , :_ 



' \ 



.'■ br-'-n obta'n-d from' 

 made 



all, SO 



■ ol iii<; eartli n < iiipiuat}, is +0-06* 

 . in}4 from 293 to 3tx), the correction 



■''■- .-— .ii'.v '. K- -^M.53' to 



I orrec- 



1 discordance re- 

 •untinj:; to !-r4*, 



NO. 2 1 71, VOL. 86] 



IhliionliiK iiUi"-ii;.; 

 vi-.ili-d .a ni-.irh ion~:. 

 in 1 111- yi-.ii ly me;in, -v', : ; . : 

 nii-nt is ri-N'i'^i-d, .md .ih. 11 



n-mou;;' '. ''■ m>' ol llus ins uol _\.-l u' '-n hi-m u\ ■ a '-tj. 



I h' ill R..\. of the moon's tabular place for 



Kjio from meridian ob.servations of the limb 



.and I'-.sS-- lioin those of Mostinj.^ A. 



rii'- 1' li' X /- eitii uiho observation- for -cussed 



by -Mr. l-.dd on the 



whole, with Inter- 



national l-ali: ;i'i' ^- : . 



About lioo douhl'-"' do with thej 



2S-inch ri-fi.etor, ini 1 _ pairs undefj 



0-5" .-.'■par.ii 'on and 15; ]).- i l-o". 



In till- io-iiii ii Jhomiisii mirror, lust| 



silvered in lihiuary, 1910, is still in good condition owingi 

 to the cover ha\ini; been made air-tight by a band of puri 

 rubber. This instrument was • . ' ' in photc^raphinj 

 .s.iturn .ind its ninth satellite, i909C and 191 



and (■, and some' of Herschela i.- ^j^h.l, the latter fi 

 idi-nti!ic.ation .ind jKisition detennination. 



Ihi- 2ti-inch r -fr.icior was chiefly employed in the photo- 

 j^r.iphic (h I rmin.ioon of the parallaxes of stars in the 

 (Iriinwich a-rroL;raphic zone, Kaprteyn's method of 

 e\))osuris on tin- >.ime plate at intervals of six months, 

 beini^ followi-d. 



As the southern declination of Jupiter made observati 

 .at dri'i tiwich impossible, the director of the Helw; 

 Obs'-rwito; \ mukriih.k- I,, contimie the observations 

 J viii, on eight nights, have:| 



■ dread \ h for measurement. 



Approx -ai > v.i \o photographs of thl 



satellit ;!iai the ommelin ephemeris il 



only 20 111 error. 



Since November, the Greenwich astrographic telescc 



has he"" ...iii.l.>x-...l ;t, th.: ,ih,a,>.M-o>'-v,- (l.-rf.rmin.-ition 



the m.i •, olume 



of th pola 



setiUi'iici-s \< 



An inter' ion now bi'ing carried out 



the obsi-rvaviTx - ta- • -.rdiiv ration of the stars of difTerea 

 mai^niiudes on tlv^ photoi^raphs of the whole sky taken 

 ^'- !-'r.-mklin-.\dani-, " ■' - ' ■.■..-:.-.• 'i^-^ ■--^-• '["went 

 I'li-s, covering; ''>le ar 



:i,i\-.- ! e, d - ''ounte 



(in twentyJ^ 



The Da!!:nL\er piioioiit lio^raph is now housed in til 

 dome of the cild altazimuth, where one quarter of 



original dome was cut ,av ' a corresponding sec 



fixed permanently in the that the large dor 



.aperruri' ihus -, cur. d '- ■ ' ''\ l>ringing it un<l 



ih.- fiX' d ■- Oi^raph record n 



cvnpl. r- , • '! (~ireonwich 



iiavia:; h phs received fr 



Dv'in ami .itorios in Inc 



Mnce iiie l>eginning or 'm.i\. oiv o; lae photoheliogr 

 observers has attended from 7 to 9 a.m.. thus adding 

 hours to the period of oh-, r\-a-;on, and also seeming bet 

 ri-sults. 



Till- mean daily sp. i of tho -.. 



was less than half that of looo, and during iiie iive moni 

 ended Marcli 31, tqii, the disc w.as free from spots 

 sixtv-seven davs. During ' '" ipproaching mil 



mum the direction of th- to bo determir 



