80 
1751, although the Nautical Almanac has regularly fur- 
nished an ephemeris. There is, however, a third method, 
which presented itself to me some time ago, and I cannot 
comprehend why it should have been so entirely neglected. 
I mean, by observations of Venus during the period of its 
retrograde motion, and, more especially, when the planet is 
stationary. 
“The delicate and faint crescent form of Venus, at the 
conjunctions, offers excellent opportunities for observation 5 
and from what I have been able to accomplish with my 
small instrument, I have every reason to believe that most 
excellent results are obtainable with meridian instruments, 
at observatories in opposite hemispheres, but lying nearly 
under the same meridian. Furthermore, at that time, 
Venus is almost twice as near to the earth as is Mars when 
in opposition, and observations upon it have the very impor- 
tant advantage that it is not absolutely essential they should 
be simultaneous, or nearly simultaneous. Again, when the 
planet is stationary, the observations of one meridian may 
be readily referred to another by interpolation, without risk 
of error, and, at this time, it is much nearer to the earth 
than Mars can be in the most favorable case. Finally,—the 
distance of the planet from the sun being about 29°, — mi- 
crometrical may be combined with meridional observations. 
In my opinion, then, it should be our object to multiply 
meridian observations of Venus about the periods when it is 
Stationary, and endeavor to obtain micrometrical measure 
ments from all parts of the earth; more especially from 
_ Voyagers.” 
After a summary of his views, Dr. Gerling continued: 
“The preceding synopsis of my paper will, I hope, reach 
in print after a while. Meantime, I beg you will exam 
ee ene — 
