212 



NAT URL 



[December 14. 



I'j! J 



Between April «nd May, however, the iwtherm of -ss' 

 pa<i*<f's into till- ii|)|xr tittiiospheri-, wli.rr, tomparativily 

 upt-akiiif^, w.iMii londilions prevail in ili- ndvci tivt- lay<r 

 from Ma\ to .S< piirnlxT. As this im tliod of plot! inn ''"' 

 rejiiilts shows t Icarly the tfinpe-raiurf variations ihroiii^liout 

 Ihr yt-ar at lii^li I'Vils, I thought thi- (liaj<rain nujjtit I" 

 intrr<'stinj;j to \iui r idrrsi. K. M I )i i i i 'i 



lnj^l«\voo<l, i...i:,;. mil Avrnuc, Harpi-mh 11. 



The Weather of igii and the Ultraviolet Radiations 

 of the Sun. 



I\ idiuiri I imi with l)i. SIi.iw'n aiiiiiipl In > \|il.iiii lli' m- 

 rii.irk.ililr wralh.r dl lliix simiiii' i ( N \ i i ici , Niu.-iiiImi y\\, 

 I vliduld liU, 1,1 (liiirl all. mil, n 1(1 .1 |)(riiu III WW whiih 

 in ;^.ii'i ,il, lull i-^|)ii i.ill\ ill ill' |i.i-l suiiini'i , (l'^'i\'s tin- 

 :ill.lili(ili ul 111' I'liinl. 1^1-1-.. M, !.:,i.,r..- .i;. l..,s.(| oil ;t 



-,. 1 i.-. Ill . \|). 1 iiti' iiu w liii li I ~ .r. : ■ .\ ~.,r . :■ . . ill' r \\ iili 

 I'lol. 1,1 n. ml (!'. I.'IKikI and ( l\,im-~,iih i , " Ihcr (lie 

 \\ irkun;; •^•■lii l^iir/u i lli).;< ri ullra\ iolli n-n l.icliti-. auf ( iast- 

 iind .in.- v.lu- i.uh.- (Ju. Ilr di,-^.v I .i, hi.-., '■ I 1 , 1,1. Il,..rj<<-r 

 Akail.llli.', ti\ .■ pai I s, ic) lo III. 



I )i . >liau sial.s llial all c i .nd il ion-- !:■ Inr a 



li. .t\ \ laintall app.-ar.d In I" |ii.^.nt, willuiul lain lalliiif^. 

 inil li.- ha-- nol |)aid all. nlimi i.i an iiiipnrlant rondilion : 

 for ill.- (iiodiirlion ol rain iuk |. i iiiii-I \i>- pi.v.nt, which 

 ran ^.lA. a^ i.nlr.^ ol (orid.n-.al ion wlun all ollni ni-( .-.- 

 ■~arv londilioiis ai.- fulfdl-d. ill.' ali--.nr.' of mk h niirl.i i-, 

 in in\ opinion ih.- i lii.f i an--.' ol lln- r.-markalil.- u.ath.r 

 of Ilii- \iar. 



In ill.- work jusi i|noi.-d w.- ha\.' il.-arh ^.paral.-il, for 

 ih.' tir^t linic, III.- dilf.-i.iil a(lion> ol nl!ra-\ i(d.I lit^hl on 

 .:;as. -, and explain. -d lln- complii-.u.-d .tf.iK <lvi.- lo ih-ir 

 ^-iniullanious i\is!i-nr.\ W'.' di-.l inu;nisli ilir.-.- a. lion-, of 

 ullra-\ iol.t li.:.;hl on du--I-fr.-i' ^a^i-s : — 



(II I'll.' formal ion ol .l.-ciriial carri.r-, of niol'cular size, 

 < .lu^.'d l)\- -..'l.clix-.' ahsorpliori of ill.- lii^Iit ; tfn' ])o\vcr 

 w hi( h ill.--.' <arri.'r^ po-.-.^-, ol jirodiu ini; condensation is, 

 arfordinj4 lo our . xp.rim.nl -, \.r\ ^ni.ill t umpared to that 

 of the mil I.i, ori;^inall\ n.iiiral, m.-ntioned under (^l. 



(2) Chrnii( al aclioii, f.^. foinialion of ozone in owj^.n; 

 this effect i> coniucttd with but small absorption of tlu> 

 light. 



(3) Formation of condensation ruulci, i.e. f(Min.ition of 

 solid or liquid prodiuis l.\ ih, dir.c 1 anion of tli" lii^lit on 

 the gases; e.g,. formalion of dioi^ of Indrou^'n p.'ro.xidr 

 from water vapour, as found h\ .Mr. ('. 1. R. WiUon, or 

 by subsequent r.aciion of th. pidduci-, form.-d wiili the 

 other components of the air. ..t,'. form.iiion of ammonium 

 nitrate and nitrite from o/on.- and .immonia. The size of 

 these nuclei depends on th. im. n-iiy of the lij^Iit and their 

 time of forniaiion. Th. ir . hi. f property is thiir i.;r.'at 

 power of ailini; as i.iiir. s ol 1 (uulensation, and the l.-irgcr 

 tli.-v ,'irc th.' mor.' .uiiv.^ in this r.sp,.ci. They possess 

 :>ni^nt.illy no .l.ririr .li.iri^r. liui cisilN .acquire one if 

 carriers of f-l.cirii ity ;ir.- siinuli.ni.'oush prodiu-'d In- 

 coming together witli Ih.s,. ; ihe pr.s.iK.- of a (liar--' has 

 no effect on their power of ai liiii.; as rondens.ilion nuclei. 



This j,^ives us the ilii. f s,nin. of nuclei in the earth's 

 .itmospher.'. If we nei,'l. ( 1 ili.- pur. !\ loe.il formation of 

 nuclei in I.-iri^.' centres of indusnx. th.-n the ultra-violet, 

 and to ;i minor d.-eire.- the kalhod.-. r.idialion of the sun 

 is chiefly responsible for the nuclei which are meteor- 

 ologically so im()oriant. 'I'his production of nuclei extends 

 from the uppermost down to fairly low-lyinij Livers of the 

 air, as the .ictive rays .ire only absorbed to .1 small . \tent, 

 and is ( hietly conditioned by the amount of ox\i^.ti and 

 ammonia present. 



Thus the lack of nuclei, and the consequent fine we.nh. r 

 of this year, can be attributed to a much diminished ultra- 

 violet radiation of the sun. This is in accord with the 

 now existing minimum of ijenernl .nctivity of the sun. as 

 characterised by the minimum of sun-spots and northern 

 lights. This view is not conir.ulicted. but confirmed, bv 

 the high temperature on tin- surface of the e.uth. .ns this 

 IS principally conditioned by the increased clearness, i.e. 

 transparency to heat radiations, of the atmosphere. 



C.^RL RaMS.^CER. 



Kadiologisch-Physikalisches Institut, Heidelberg, 

 December q. 



" Draysonia.' 



ol 



ri\ !• 

 1 I.. 

 |. ■■ 



. 11 - I., l! 



ill in ju 



misappreli' 

 ir of insi't 



ility to do full jus 



aiptinti to briiiii his 



liljl it i- 



-is ^\:,iM>' 



und. I I 

 aft. r I 



collsiil. ■ ■ \. ■ I \\ j,e h' 



sc:nc.l\ who has 1. 



" .N.uiii. ... \,,i...,.,.. ... W-. Jul iiKjf- than s«;v»! 

 ve.us (.111(1 h.i- ina(.l. n;iuti(al astronomy an occupati. 

 ri( re.nion) ".onlus.> pi.cession with ab<*rration," ,.: 

 ih.r.foi. " s, .ir(.l\ lill.-d " lo d.-.d v.ith the subject. 



^>lur i.\i.\>..r in.i\ |)ossibly be .'i [ir"f. -sionn! astronom. 

 (who p. rli.ips dislikes .inythiiij^: 

 aitordani. willi the le.xt-liuoks 

 aw.ir-- thai in the l.it. r " N.'uilnai .Mniana(s tii. 



preossioii " in the ( ;it.iloi4ue of si.irs has been sub~- 

 for tli<- old and betn r t. rni " .uinual variation," wli 

 Used in the " Nautical .\lniaiiac " and by oui 

 n(im<rs for as many \e,irs as I can remember 

 or I'So.s, when th.- i han^e was made. Previous lu litis n 

 word pre ( . ssion lud b* .n mainly confined to precession . 

 ill'- equinox, s (d. .lit with in section it of " Dravsonia ' 

 wlii(li at pr. s. Ml is .tbout 50" anil i< totally distinct froi 

 what a>.ir(jnomi-rs term aberration, but which I prefer t 

 call annual motion of the pole. 



Your reviewer further states that I have computed th 

 precession of many stars by Drayson's method, and that, 

 this proves .mything, it proves the correcfnes": of tl 

 "Nautical Almanac." This is a mist. 

 inversion of my process. Insi.ad of havi: 

 calculated the so-called precession of manx s 

 used the precessions, so accurately lJU' n in th- 

 .Almanac," in order to find then from the .-un. 

 annual motion of the pole; and I nav. shown that tl 

 so-called annual precessions of the stars, all varying i 

 amount and direction, both in ri^ht as,, nsion and declin. 

 tion, are exactly accounted for by on. sint;le movement ■ 

 the pole of about 20*, which produces the apparent annu. 

 precession as obtain-d by observation and recorded in ti 



Nautical .\lmana( .' th. accuracy of which I have nev- 

 impugned. 



1 am unable to iind.istand wli\ \our reviewer questior 

 my statemeiit that Mr. Stone, the \nto Radcliffe observ- 

 at Oxford, made the error of sid, r- ;il time erroneous to th 

 extent of 4i-5is. in 1892. A r.f. rence to the Royal .Astr. 

 nomical Society's notes of Mardi, iS.)4, will show that 

 am correct. Ak.kknon i>E Horsfy 



M'lcombe Hous. , (.•,,, \ov. rub. r 10. 



1 .\M ijuite willing to admit that I hav n. 

 the gallant .-Xdmiral, and accept unreser\'(il\ his -; 

 that he does understand the differenc between pr. 

 and aberration. In my own defenc- vou will p. ..,,., 

 permit me to quote the passage which misled me. 



" Possibly I shall be told that 1 have found a mar. 

 nest, and th.it it has been known all along that th. 

 .isci iision of a star and its annual precession in d 

 tion are functions of the annual motion of the pole, ar 

 that such motion can be found in the * Nautical .Mmanac. 

 and is properly termed aberration." 



The italics are mine. To my inind this sentence admi 

 of only one construction ; and, if I have been so unfortuna^ 

 as to misconstrue it, I have no doubt I have not correct! 

 apprehended the author's meaning in other places, ar 

 therefore it is of little use to discu- -ral poin: 



raised. \! viewer. 



Dust Explosions. 

 Proi. r,Miow,\Ys brief article on dust explosions in 

 N.MrKE of No\ ember 30 is very timely; but readers of it 

 would receive the impression that the true cause of th' 

 explosion at the Tradeston Flour Mills, Glasgow, in 187. 

 was first made known in the report of Profs. Rankine and 

 * Macadam. This is not the case: the fact that flour-mill ex- 



NO. 2198. VOL. 88] 



