438) REPORT—1883. 
a bulb of excess. On March 31, at 11,18, it indicated 201:5° Fahr., and was still 
rising. ‘The shade temperature was about 62° Fahr., and the barometer stood at 
187 in. The fine morning of May 24 gave, at 10.54 am, S.R. 191° Dry 
bulb, 60:9°; wet, 482°. Barometer, 18-7 in. Tension, 0-232, or 439%. This ereat 
dryness of the air causes an immense amount of evaporation from the surface of” 
Lake Titicaca. The 4,400 square miles in area loses about 3 feet in depth, mainly 
by evaporation, or about 2} cubic miles of water, in the months May to December: 
inclusive. At:the driest season there is always more water running into it than out 
of it. On June 2, as I said before, I at last received my solar spectroscope and the: 
remainder of my long-expected instruments. Wishing to give this apparatus the 
best possible chance, I immediately returned to Vincocaya, the highest point at my 
command, where the pressure of the air was about 1:2 in. less than at Puno. T 
did not, however, find the air appreciably clearer; what little was gained by the 
small decrease in density was about compensated by a slight dust-haze, resulting 
from the action of the regularly recurring afternoon breezes on tlie sandy pampa. To 
my great disappointment several prisms of my old-fashioned Browning solar 
spectroscope had been much damaged on the journey, so that its action on the sun 
was much impaired. The chief observed fact was the unmistakable increase of 
brightness towards the violet end of the spectrum. This was particularly shown 
by the facility with which the solar prominences could be observed in the Hy, or: 
‘near G’ line. The prominences, in fact, could be seen with about equal ease in 
any of the four lines Ha, I),, F, or Hy; nor was a large dispersion at all as neces- 
sary as at the sea-level. The slit could also be opened ad libitum. The small 
spectroscope already spoken of, when used with a bit of cobalt glass, showed quite a 
range of lines above great H,. At this station I completed the drawing of the 
southern part of the Milky Way, that I had begun at Puno. I also frequently 
viewed the zodiacal light with the small spectroscope, but although that light was so 
intense as to be visible when the moon had passed the first quarter I could never 
make out the faintest trace of lines in its spectrum. There was nothing more to be 
seen than a short continuous spectrum from just before E to a little beyond F. 
There, for the first time in my life, I saw the sun-spots by direct projection 
of the sun’s rays through a small hole into a darkened room without the aid 
of any lens whatever. I was astonished what an amount of detail could be made 
out in this simple way. From Professor Peters, of Clinton, however, I found that 
this plan of viewing the solar spots was used fully two and a half centuries ago ; indeed, 
a full account thereof is given in Scheiner’s “Rosa Ursina.” It is strange, indeed, 
that not a word of this, as far as I know, is to be found in any of our modein 
popular works on astronomy. On talking the matter over with Lord Crawford 
at Dunecht a few days ago, we tried this experiment, I may say at random, 
in one of the domes there, and immediately made out a spot by the help of an 
accidental hole in the roof. It will certainly be remarkable if it does not turn out 
that the sun-spots have been seen in this way long before the invention of the 
telescope. At Vincocaya, too, I again made a number of solar-radiation and other: 
meteorological observations, of which I give the most striking ones, taken on a 
truly characteristic day. I was most comfortably quartered in the house of the: 
genial and kind-hearted station-master. Round this house ran a wooden platform. 
on which, at daybreak, a family of goats capered and clattered about in the thin frosty 
air, At 6.50 a.m. the sky was intensely clear; the temperature, 7:1 Fahr.; the 
barometer, 17-4 in. At 7.48, the sun having of course risen, the thermometer had’ 
risen too, and showed 18:9°; the depression of the ice-covered thermometer was 
3:0°, the tension 0-045 in., and the percentage of humidity was 43}. By 8.5 
these quantities had changed to 5-7° depr., 0045 in. and 40 9%; but the black- 
bulb thermometer already registered 107° (corrected), and the goats were actually 
basking in an air-temperature of 19:9°, or twelve degrees below the freezing point, 
and the fowls feeding ; and now came a rapidly ascending series of sun-temperatures, 
1303, 187, 1503, 154, 169, all within the fifty minutes from 8.10 to 9 A.m.; the 
sky excessively clear, Venus then about 11’ diameter, shining with an intense: 
lustre in the dark blue air. At 9.36, when the black bulb was no less than 180°, 
the dry bulb was still 29:8°-30°, or 2° below the freezing point. At 1.56 the- 
