254 



NATURE 



■ !v have the 

 t so easily 

 mj; most attcn- 

 prpponderatcs. 



to a copy of 



<\o of 



: tlask 

 about 



am is 

 on to 



id the 



^111 



roj^ion IP. 

 anoma'i 

 tho \va\ 



wlnii ( 1 r .. itli the kiKiwn 



\va\ 's, -^hdw ihat ill both cases the 



i^lilvMirhood f)f 4 centimetres is one of 



!ivo indices innca-^in:' as 



Messrs. F.. R. \orm\n and Co., 26 Great George 

 . IiavT is-;u((l .1 pamphlet dcscribin}:; the Sytam 



.kiiii^ noti s and filing papers. The system 

 ; 1)1 ini'thods of hiiuiin^ toirrfthcr loose sheets of 

 which can bo tradily introduced or removed or 

 M^ition, forininf4 a compact book. There arc 

 t kinds of mechanism suitable for binding 

 together sheets of various sizes, which range from 3x2 ,'7, 

 to 13^X0' inches. The system appears to be quite prac- 



consi 

 papoi 



rh," 



tical ni. ' 

 in wli; 



t\v 



tabs on th( 



verv easy. 



application ; we have seen a large ledger 



are arranged for the D schedule 



f the International Catalogue, the names of 



of the schedule being indicated by projecting' 



odgos of the sheets, which renders reference 



" Remarkable Eclipses " and " Remarkable Comets," 

 both by Mr. W. T. Lynn, have just been issued in their 

 eleventh and fifteenth editions, respectively, by Messrs. 

 Samuel Bagster and Sons, Ltd. Both have been brought 

 right up to date, and the most remarkable feature of each 

 is the enormous amount of information compressed within 

 so small a compass and sold at the low price of 6d. each 

 net. The former volume includes notes on the most re- 

 markable eclipses of the sun since 1063 B.C., and of the 

 moon since 721 B.C., while the second briefly describes all 

 the remarkable comets of which history speaks, even 

 though it be with far-off whispers. An excellent drawing 

 of Halley's romct, as seen by Miss E. M. Phillips at 

 Barbados on May 17, 1910, is an additional feature, new 

 in this edition. 



Tin: .\pril issue of Mr. C. Baker's quarterly classified 

 list of second-hand instruments contains a description of 

 more than 1500 pieces of scientific apparatus for sale or 

 hire at Mr. Baker's second-hand department, 244 High 

 Holborn, London. 



In Mr. E. P. Stebbing's paper on " Tree Planting in 

 Town-,'" on p. 197, col. i, of N'\TrKF of April 6, the 

 word " I'.tna " should have Iv ,-n "Everest." Mr. 

 Stebbint^ asks us to correct this error, which was made by 

 his typist, and was overlooked by him in the proof of the 

 paper submitted to him. 



\i'i:i!. 20. I<M I 



OUR ASTF^^ ^'^^^f f^' ^ ' f^'^ J ' '^f V 



NO. 2164, VOL. 86] 



.Ai'Kii, .Mi;ti:ors.- 



April meteoric show'i \m u. ..■.- ^..u .%,.-,. 



\»: little moonlight. With clear skies it ought to 



s.iiisf.ii lorilv ohsMVid. hilt the charai tir of its retur 



.line abundaiK • •: 108 y»..: 



ince the date .1 There is i 



ri-.isun to .itit i( i|).ii«- a brilliant cxhiuiuon 1' -■.••- > 

 the sky should be vigilantly watched on ti 

 .April 20. 21. and 22. so thai if the shower ac; 

 it in:i ften of short <i 



and I: ')«;frved bffor'- 



or .ifti r .Xpril 24. 



" I'rom ohserv.'if ions n 

 tainlv believe that the radi.ini ])oini is iianii- 10 ui'- sn;i .• 

 easterly motion as that which affects the emanating centri 

 of the Perseids. But the April stream supplies so f' w 

 meteors, except on the date of maximum, that it is r-x- 

 tremely difficult to get the precise position of the rndinr* 

 po'fit on tho 17th and i8th, and 23rd and 24th. O' 

 v.oul'l do w'll to gather as many apparent paths as 

 on the nights just named. Records of meteors ob* 

 two stations would be specially valuable as sf-; 

 indirntf tho point of radiation accurately. On /\},... . . 

 ii|Oi, i:;h. Kini., a ?)ri:^hr I.vrid was recorded by Proi. 

 Hirsi hd .'it Sk)iii>h. and liy the writer at Bristol, and th" 

 ra(iiant was indicated at 2(')<'>° + 23° ■ This object afforded 

 ovidiniT- that the Lvrid focus is a changeable one, for if- 

 centre is at 270°-|-32° on .April 20. .Additional observation- 

 of similar character would supply valuable details bearintj 

 on an interestinr: ff '>»■•-" -f ti^^ '^'-play." 



Till-: .Sim:ciri :ive. — Spectrograms < ' 



Nova I-ar«r^:e I'-'sdam Observatoi\ 



on January 1 . 7 - 'scribed by Prof. 



Miincli ii; ^ ■ I'hc Xachrichteu. 



The V taking the mean 



measu; lines as norma!, 



and th.;; :;ii' rpo!.!! ;:;.; !!v. ii;';i'r iiv.isures. Naturally, n<. 

 rigid arcurarv is elaimed for th'' values as being absolut'-. 

 but tlie table is a useful record of the lines seen and of 

 their various intensities and characters. On January 7 

 H7 and H5 were sharply defined on the red side, but 

 diffuse on their more refrangible edges, where they were 

 accompanied by broad absorption bands : the maximum 

 intensity lay on the red side of each line ; on the other 

 hand. He and Hf were equally sharp on both sides. The 

 usual decrease in the intensity of the continuous spectrum 

 took place, and on January 23 it was much fainter than 

 on January 7. Prof. Miinrli di.scusses the intensity curve 

 of the nova spectrum, and by a comparison of the distri- 

 bution of energy therein shown with that given by several 

 stars of the .A tvpe, he derives an energy curve for the nova. 



Tm; Diiii-KKNr Ouai.itv of the Light Reflected from 

 Various Parts of the Llnar Surface. — It will be re- 

 membered that Prof. R. W". Wood found recently that, 

 when photographed in ultra-violet light, various features 

 on the moon presented different appearances from those 

 presented on oidinarv photographs. 



Working: arlottenburg Tedmischen Hochschule, 



Herren A. md B. See^ert have carried the in- 



vestigation a step further b\ usin' two screens in connec- 

 tion with a reflector, on. of which transmitted light <A 

 wave-lengths 360-330 /x/x, tiie other light of wave-lengths 

 700-600 fifi- -A comparison of the plates so obtained shows 

 remarkable differences of illumination, especially on some 

 of the surfaces of the maria. The liigher parts of the 

 lunar surface, especially in the region of the south pole 

 and about the ring mountains of Copernicus, reflect hardly 

 any ultra-violet light, while the north polar regions reflect 

 a great deal. By projecting the two photographs through 

 complementary screens, the differentiation of colour is 

 brought out remmL-nhlv, the Sinus Roris and Mare 

 Nubium show;- . '^able variations (Astronomische 



Sacliriclitcn. Niv : " 



The Pvrhfiiometric Scale. — A paper with important 



bearing on r'^ ..■^•: ,- .^f the value of the solar constant 

 is publishe ' '\'ibot and .Aldrich in No. 3. vol. 



