Report of Observations on the Transit of Mercury. 143 
sky, was seen, about an hour previous to the first contact, to be 
gradually moving from west to east, leaving from the western 
horizon upwards, a very pure sky. We watched the line of sep- 
aration with much anxiety as the moment of first contact ap- 
proached, and had the satisfaction of seeing it clear the sun al- 
most precisely at the desired instant. At Cambridge, Nantucket, 
and Providence, the ingress was lost in consequence of clouds, 
but the latter part of the phenomenon was favorably seen; at 
Hudson, Ohio, the weather was fine until nearly 5 o’clock P. M.; 
and at Cincinnati, the four contacts were all in view. 
We have before us accounts of observations on this interesting 
phenomenon, made at Providence by Prof. Caswell, at Nantucket 
by William Mitchell, at New Haven by Prof. Olmsted and Mr. 
Francis Bradley, at New York by Prof. Loomis, at West Point 
by Prof. Bartlett and Lieut. Roberts, at Philadelphia by Prof. 
Kendall, at Washington by Lieut. Maynard and Profs. Coffin 
and Hubbard, at Charleston, S. C. by Prof. Gibbes, at Cincinnati 
by Prof. Robinson, and at Hudson, Ohio, by Prof. Nooney. 
The observations at Yale College were rendered, by peculiar 
circumstances which it is needless to mention, less accurate than 
we had hoped for; so that we could not confide at all in our first 
contact, nor entirely in our second, or the first internal contact. 
The want of a suitable observatory for using our ten feet refractor, 
(Clark’s telescope, ) prevented the complete success of these two 
observations with that instrument; but we had good opportunities 
afterwards of viewing with it the physical appearances of the 
phenomenon, and of observing the two last contacts. The slow- 
ness of the planet’s relative motion, being only about an arc of 
one second in twenty seconds of time, and the want of a distinct 
indentation upon the sun’s limb, like that which marks the com- 
mencement of a solar eclipse, conspire to increase the difficulty 
of being certain of the moment of ingress; while the eagerness 
of the observer to catch the first glimpse of the real object, whose 
image is so vividly painted on the mental vision, exposes him to 
the danger of transferring to the skies what is present merely to 
the eye of the mind. Prof. Loomis (who, however, unfortu- 
nately, had the use of only a small telescope, wholly unsuited to 
so skillful an observer) remarks, that he was unable to see the in- 
gress, until the planet had advanced one-third of its diameter up- 
on the sun’s disk ; and he deems it impossible that the first con- 
