The Birmingham age-herald., 1912-11-17
INVITATIONS OF DAYLIGHT
Results of Researches and the Diffi-
 culties of the Problems Presented

From London Nature.
 The problem of artificial daylight has led to innumerable researches. There are many industries where an artificial H. luminant resembling normal daylight would be exceedingly desirable. It would be a boon to florists, artists and others whose work requires a fine dlscrimina- tion between delicate shades of color
 The most recent achievement in this direction is that of Dr. Kenneth Mees, described before a meeting of the fllum- mating Engineering society in London this year By O combination of gelatine involving the use of a newly discovered blue dye. he states that very perfect resemblance to daylight is secured, and that the results are remarkably perma- nent. The absorption of light is natural ly considerable (amounting to about S5 per cent, but for the special work for which this lamp is intended such a loss in efficiency is not of very great conse- quence in comparison with the advantage of being able to extend the hours of work after daylight has ceased.
 It is not suggested that lamps of this kind would come in general use as a sub stitute for artificial illuminants of the ordinary kind. Indeed. the impression is that people rather prefer the more golden hue of artiifical light in the evening. This hue has become mentally associated with comfort, and r1rshiy ! efee to carry out the sequef 3f 1aa tf1s daylight to the warmer raz oz s4nza The idea is rather to use laae a4lesa' daylight units for special T30o example it would doubtlasA Ii a tirap- er's establishn hA all recess
 illuminated in ln aF sa net custom
 CTS, in choosif materials uosld be able
 to compare tiei q|arr uaasr this light
 with their appra. dtser hN fI at1inary ar
 tihcial illuminz ufs
 Current LitefaiNra remarks There is
 one question tea ea inpor ant bear ing on these sGh nA sa1sF. the diff culty in declf e fa1 -rd white light. The re aie1s f fr lichols of Cornell uniye silp that the
 spectrum of e'es considerably with different 1ciiiois and at
 different altiti V9n Especially.
 where period elTe he trans
 nitted light atra .l atA acter, this is so. But in eeaa pears that throughout q tat4 te af the day
 the quality of 9a EHsse sky does not vary very feats tnd 9flicate color work would paHf os acus 1der these conditions
 Every illum ling gfeee snows, ac- cording to Wi5enlr.f ksrnif ,ert, writ ing in the Ne Tfx Tif4ef. fnAt 1t is not
 a very difficui faaticr tp pred nee a light under present erdcns Wiliet is the ex- act equivalent q afsI se Eht. There
 are just two aoys 1c 1c sore Of ac- complaining thtf ead EfthaF sou add to
 given illur 1ans rays cf the color which it lack c- sfed hF Dr. C. E. Kenneth Nee rsIee 1th hie rays are eliminated by ffa sst atsat may be
 called an opt
 Artificial csrt tas pf11aoly not the best light. oi3ig a1 fnta acturer of textiles, the agt ts dfhcS apher-in a word. the ma fTitez sias business in
 hte 1t Is to II tc4 c1lars. fgaaly demands an exact equ iantsef aaNifeat Most O. us would be a4ift tet with a light of pleasing .ct laf cient
 How inefAelt s esent lamr may well b 1s ,mparing it with that of eiis He@ udies made
 many years A@e eT If- tel P. Lang
 lev and repe a1 nHre ly and more deliberately pw is and Coblentz
 in this coun' srw iaL tlie firefy's ef- slciency is ''' W ent--that its l light Is vel producing the
 most enicie- at'HFH ik Known, only l about pc eut tt tnerxy of the coal pile is' <@e fn tfe ftrn of visible 1 radiation. 1 a is waisted, chiefly by n esgi ,. and in pro-
 ducing he shat e not visible
 Yet even s 0; ste thousand
 candlepow lse him to fit