4.46 Scientific Proceedings, Royal Dublin Society. 
references to diminutions of sun-light extracted from historical 
works. 
At the June meeting of the Royal Astronomical Society Dr. H. 
Draper gave an account of the researches which led him to point 
out the existence of bright lines of oxygen in the solar spectrum. 
Since 1877 when he first announced his results, he has considera- 
ably improved his instrumental means. The most important im- 
provement is the “spark compressor ” to confine the spark between 
the poles. Ordinarily the spark pursues a zigzag course, but by 
means of two plates of glass it was confined to a narrow space in 
a plane through the slit. The glass, however, would not stand 
the powerful sparks, and eventually soapstone was substituted. 
In a block of soapstone a cavity is formed of the shape of a 
Pliicker tube, 7.e., two chambers connected by a narrow passage, 
and one side of the latter is cut away so as to form a narrow 
chink directed towards the slit of the spectroscope. The 
electrodes (one of them being of iron) are introduced into the two 
chambers, which form reservoirs of intensely heated air, and thus 
keep up the incandescence. With this arrangement sufficient 
brightness of spark was obtained to allow of the use of a large 
dispersion with a spectroscope having two bisulphite of carbon 
prisms, with a collimator of twenty-six inches, and telescope or 
projecting lens of six feet six inches. Thus photographs had been 
obtained on four times the scale of those published in 1877. The 
great difficulty is, that even with these powerful appliances the 
light obtained is only equal to that of a single candle illuminating 
a slit of zd5 inch, and this is enfeebled by being spread out into a 
spectrum more than two feet long. Dr. Draper’s communication 
was followed by an interesting discussion as to the reality of 
the bright lines in the sun-spectrum. (Obs. III., p. 67 and 
foll.) 
An attempt to explain the existence of bright lines of oxygen 
in the sun has been made by Mr. R. Meldola, in a paper published 
in the “ Memorie degli Spetroscopisti Italiani,” vii., pp. 91-100. 
The author of this paper supposes that somewhere in the higher 
regions of the solar atmosphere, above the chromosphere, the 
temperature falls off sufficiently for some kinds of chemical com- 
bination to take place. In this “zone of combustion” oxygen 
and hydrogen, for instance, would enter into combination, and 
