An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

1[RANS'IT Ot'1' IIO Tl lNF'TIOR PLANET'S,.191
since it is easy, by article 308, to determine, at, tflat time, tlhe
n/atio of her distance from the sun to tlhe eart.lh's distance, it is
a mattelr of gireat interest to astronomy to harve the parallax of
Vcl118s, \whtlel thus sitluated, accurately found. F'or this purpose, the government of thle TUnlited States, inll 1849!, sent anl
exp)edition, under Lieutenant Gilliss, to Chili, in oirder to take
obstervations oln Marals and Venus, especially the latter, durinilg
1850, 1851, and 1852, in concert. wit.h the Observatory at:
W'aslting'ton.'tlcse observations seem to indicate that the
solar parallax is a little less than stated ablove, probably nearer 8".5 than 8",.6.'x'
3 1 9. Dur'ing the transits of Velmus over the sun's disk< i
1.761. and 1.769, a sort of penullmbal light iwvas observed around
the planet by severtl astronomers, whlich was thou glit to indicate an at eostjtle. This appearance was paurticularly olscrvable while the planet vwas colling onl and going, off the solar
disk. The' total immersion and emersion wer e n)ot inlsta-ltaneous; )but as two dlrolps of w\ater when about to separate folrm
a ligament between thelm, so there was a dark shade stretched
out betweelln Venus and thlle sun, and when tlhe ligament; birokc,
the l planllet seemed to have got, about an ci'hlth part; of hell
di<ameter friom the limb of the sun.' Tlhn1e pIesene of an atMlos)lherc is also indicated by appearances of t\ilight anld
illdicatiotns of a horizolntal refl'actiolln.
Althoughl no satellite luas hitheirto been discovered attending
either;1Mercurlly or Venus, y1yet suspicions ha ne, at dif1erent
tinles, been entertained of a satellite belomnging to'Venus.:None ]has been seent in any of the tranlsits of Venus; and althioughl t.he distance of tlhe satellite (if oino exists) fiom the
pr'ilmary might. have been too great to be projeicted withl tllo
primary onl tle silun, yet its absence on each of these occasions
htas strenlgthenedl tle belief of asthronomlers that no such satellite exists.
I co Astron. Journ,, Oct:. 1858. - Edlil. Itncyc., Art. Astronomy. 1!ind.