CKLESTIAL DAY OBSERVATIONS. 
109 
m? «atlsfaction, as the discoverj of real causes, not imaginary, 
in the physical phenomena, is my only object. 
I have the honour to be, 
Sir, 
Your most obedient Servant, 
J. A, DE LUC. 
IVindior, Sep. 14, 1813. 
IV. 
Olservalions on the Celestial Bodies, made in the day-time ; 
particularly on the Planet Venus, with , some new Deductions 
in relation to that Planet. In e letter from Mr.T. U'CK. 
rri''HE following communication contains sjsecimens and re- 
-IL suits of several hundreds of observ.ations, made with a 
view to determine the following particulars. 
1. What stars and planets may be conveniently seen in the r.irtirnlar« to 
. day-time, when the sun is above the horizon ? hv 
2. What degrees of m.agnifying power are requisite for dis- vaucn-. 
tinguishing them ? 
3. How near their conjunction with the sun they may be 
^ seen. 
4. Whether the diminution of the aperture of the object 
glass of the telescope, or the increase of magnifying power, 
conduces most to render a star or a pianet visible in day-light. 
Observations, similar to some of those here staled, liave, 
doubtless, been made by astronomers, and may prc-bably be 
recorded in certain Scientific Journals ; but as the writer of 
this had never seen any of them in those Journals he has had 
access to peruse, and as they are not to be found in the largest 
systems of astronomy he has consulted, he was induced to make 
them for his own satisfaction and amusement, and they are now 
communicated for the information of those who may not be 
disposed to undertake the same labour, and who have no access 
toother sources of information. Some of the observations, 
in relation to Venus, it is presumed are original. 
The observations were made by means of a small equatorial 
instrument, surmounted with a telescope made by W. and S. 
.Tones, 
