44 AF KLEKCKER, EN HYPOTES OM DET »RÖDA SKENETS» UPPKOMST. 



floating above us, or interfering with the view of the heavens. 

 These only appeared about once in five days in any considerable 

 quantity. 



A raore important quality of the atmosphere was caused by the 

 dust-haze, which was ever more oi* less present, though sometimes 

 in vastly greater quantities than at others, and was precisely that 

 which injured, or rendered impossible, daylight observations of stars. 

 Where this dusthaze carae from or went to we could never teil; but, 

 when present, we could easily distinguish its banks, or strata, as 

 they stretched away and Condensed in perspective towards the hori- 

 zon. There were often several strata, one above the other, and 

 mutually separated by very clear and sharplydefined spaces of 

 atmosphere. When, as was sometimes the case, the summits of 

 Grand Canary, or of Palma, rising high above the sea of clouds, 

 pierced also these upper strata of dust-haze, w.e had, from Gua- 

 jara, the curious phenomenon of. zones of blue mountain alter- 

 nately distinct and again indistinct almost to invisibility, and 

 yet no cloud or other recognized impurity of the atmosphere in- 

 tervened. 



Being above much of this dust, though perhaps not the 

 greater part of it, we were evidently better oflP than an obser- 

 ver at the level of the sea, when pointing to a zenith object; 

 but for a horizontal one we were worse off, from often being in, 

 and then looking througli the whole plane of the Stratum, and 

 so experiencing the maximum of its light-stopping effect.» 



N:ris I och II, fig. I, framställa de förändringar i utseen- 

 det af den röda ändan af solspektrum, som vid detta tillfälle 

 iakttogs vid olika solhöjd och från olika höjd öfver hafsytau. 



Af den nästan fullkomliga likheten i solljusets absorptions- 

 förhållanden vid detta tillfälle och under de dagar då ifrågavarande 

 fenomen uppträdt, ådagalagd genom uppträdandet på ett lik- 

 nande sätt af de telluriska spektrallinierna B, a och d; som ej 

 härröra från vattengas (jemf. spektra II och III, fig. 1), kan 

 man således antaga, att ett och samma ämne vid begge tillfäl- 

 lena orsakat absorptionen. Den mycket olika solhöjden vid dessa 



