TRANSACTIONS OF SECTION A. ABM 
myself to regular hours of making the readings, but noting down the chief facts as 
often as practicable. When the moon was in the way I examined the brighter stars 
of the southern heavens for duplicity, and was rewarded by the discovery of several 
very close pairs that had escaped Sir John Herschel and other observers—e.g. 
8 Muscee and H Velorum. On several evenings the definition was almost perfect 
witha power of 400. On the finest moonless nights I sketched the Milky Way, and 
with a very small direct-vision spectroscope of Dr. Vogel’s arrangement I swept 
the southern part of the Milky Way on the plan advocated by Professor Pickering, 
and succeeded in finding a few minute planetary nebulee and several members of a 
special class of stars with most remarkable spectra, of which y Argus may be taken 
as by far the most remarkable specimen. I feel almost sure that the spectrum of 
y Argis must have been observed at Melbourne or in India, although I have not 
met with a note to that effect.!| I think that fully one-half of the light of this star 
is concentrated into four lines, three of which are close together in the neighbour- 
hood of D, while the other is far away in W.L. 467, and is apparently identical 
with a line in the Stephan-Webb nebula, in the nebula near the north pole of the 
ecliptic, and also in G.C., No. 4,964. In the fainter specimens of this class, of 
which I found some five or six, the three yellow lines become merged into one, so 
that the spectrum apparently consists of two bright lines or bands, very far apart, 
and connected merely by a very feeble spectrum somewhat stronger in the middle 
of the space between these lines—a spectrum closely related to those of the Wolf- 
Rayet stars in the Swan. 
‘Both at Vincocaya and Puno I tried in various ways to get a view of the sun’s 
corona or prominences without the spectroscope—for instance, by bringing the top 
of a telegraph-pole or the corner of a roof between the eye and the sun. I was 
astonished at the small degree of illumination of the atmosphere even in the 
immediate neighbourhood of the sun, but still I never could see any certain 
indication of the corona. I believe, however, that the experiment is well worth 
repeating, especially if photographs are taken even with an ordinary camera in 
place of merely trusting to the unaided sight. I also directed the telescope to the 
brighter stars and planets in the daytime, but without any special results, except 
that the images were somewhat brighter than at the sea-level. I never succeeded 
in seeing any other stars or planets except Venus near noonday, but Sirius and 
Jupiter were both plainly visible with the naked eye from a quarter to half an 
hour before sunset. Canopus, too, was plainly seen one minute before the sun’s 
centre attained a zenith distance of 90°. Under fair conditions a Centauri and 
Mars might be added to the number of daylight objects, but there the list would 
probably end, unless an exceedingly elevated station were selected. I may add 
that nearly all the persons that I spoke to on the subject had frequently seen 
Venus with the naked eye in the daytime. 
‘This great transparency is associated with, and probably due in part to, the 
extreme dryness of the air. So dry, in fact, is the air that even the most extended 
hygrometrical tables do not suffice to reduce my observations satisfactorily. I can, 
therefore, at present only give the results for a specimen day or two—yresults 
calculated by Regnault’s formule. 
‘Monday, May 7. 
A.M. P.M. P.M. 
0:42 10:0 10°54 11-48 12°18 1:12 4:18 7:36 
Tension in, *083 133 123 ‘111 114 ‘110 122 121 
Percentage 4] él 27 24 25 28 37 54 
‘The direct solar radiation was also very intense. The black bulb thermometer 
Thad with me contained in the glass covering a small amount of aqueous vapour, 
and was only graduated up to. 205°, or rather only to 202° Fahr. as there 
was a negative correction of 3°. The tube ended a little higher up, without 
1 It was observed by Respighi, at Madras, and by Le Sueur; sez Secchi, Le Soleti, 
German edition, Sect. 71. Note added Nov, 12, 1883, 
