Mr. Schroeter’s Observations , &c. 
in effecting the measurement of Vesta, with the same power 
of 288 by means of the 13-feet reflector, with which that of 
Ceres, Pallas, and Juno had been made; and when viewed by 
this reflector it also appeared exactly in the same manner. 
Of several illuminated discs, of 2,0 to 0.5 decimal lines, which 
I had before made use of for measuring the satellites of Saturn 
and Jupiter, the smallest disc only of 0,5 lines could be used 
for this purpose ; by it the rounded nucleus of the planet Vesta, 
when the disc was at the distance of 61 1,0 lines from the eye, 
appeared at most of the same size, and I must even estimate 
its diameter as ~ smaller. If therefore, we attend, not to the 
full magnitude of the projection, but the estimation just 
mentioned, it follows by calculation that the apparent diameter 
of the planet Vesta is only 0,488 seconds and consequently 
only half of what I have found to be the apparent diameter 
of the fourth satellite of Saturn. 
This extraordinary smallness, with such an intense, radiant 
and unsteady light of a fixed star, is the more remarkable, as, 
according to the preliminary calculations of Dr. Gauss, there 
can be no doubt that this planet is found in the same region 
between Mars and Jupiter, in which Ceres, Pallas, and Juno 
perform their revolutions round the sun ; that, in close union 
with them, it has the same cosmological origin ; and that as 
a planet of such smallness and of so very intense light, it is 
comparatively near to the earth. This remarkable circum- 
stance will no doubt be productive of important cosmological 
observations, as soon as the elements of the new planet have 
been sufficiently determined, and its distance from the earth 
ascertained by calculation. 
Lilienthal, May 12, 1807. 
