ACADEMY OF SCIENCES. 11 
of the diameter of the planet. These were made to study the question of 
irradiation. During this time there was no sign of an atmosphere or haze 
around the planet. In these different measurements about 150 micrometer 
readings were taken. I should here mention that Mr. Tittmann, the first as- 
sistant astronomer, also observed the second contact with the Hassler 3-inch 
equatorial of the Coast Survey, and noted no ligament or band. 
After diameter measures came thicker clouds, but fortunately at noon they 
broke away, and with the Coast Survey meridian instrument No. 2, I was en- 
abled to observe the meridian transit of the sun’s first limb over nine threads, 
the first limb of Venus over eight threads, the second limb of Venus over 
eight threads, and the second limb of the sun over six threads. Mr. Titt- 
mann with another transit measured the difference of declination of the up- 
per limb of the sun and both limbs of Venus by eighteen micrometer readings. 
These meridian observations and the diameter measures were not contem- 
plated by the Commission. 
Then the weather thickened and threatened rain; but at third contact broke 
away slightly, and I was defeated in the third contact. Just a few seconds 
before, I had the Jine of separation very narrow and well defined, and with- 
out ligament, but the clouds deadened it, and even without colored glass it 
only cleared to let me see that the planet had broken across the sun’s limb 
about five seconds; thence to close, dense clouds. 
During the day there was no time after 10 a. mw. when the sun shone from 
a blue sky. The upper stratum of clouds acted as a screen to the sun’s heat- 
rays, and the atmosphere was quite steady. Objects at a distance were dark 
but clearly defined. 
Of photographs we got none near first contact; only began to receive them 
when the planet was half on. After that we obtained about sixty good ones. 
Altogether, with the second contact, the micrometric measures, the merid- 
ian transits, and the difference of declination, and the photographs, I believe 
we have more than average satisfactory results. We did our best; there 
was no hurry, no jar or clash or hindrance; everything worked smoothly and 
like machinery, as by our practice and drill we had anticipated. 
Our observed first and second contacts were about 1 min. 45 seconds after 
American Almanac data, and about 3 minutes 30 seconds after the English. 
The third contact was near the time of the American data. 
Enough. Ina subsequent letter I will place before the Academy my opin- 
ion of methods and instruments and elevations to be chosen for the transit of 
1882. 
Dr. Gibbons read a paper on ‘‘Climatic Changes in California.”’ 
W. N. Lockington read a paper on ‘‘ Sponges.” 
