62 NOTICES OF THE MEETINGS [May 2, 
WEEKLY EVENING MEETING, 
Friday, May 2. 
Tur Duxe or NortHUMBERLAND, President, in the Chair. 
Ture AsTRONOMER ROYAL, 
On the Total Solar Eclipse of 1851, July 28. 
Tue Lecturer remarked that the subject which he had suggested 
to the Managers of the Institution for the present Lecture might at 
first sight appear meagre and common-place, but that he believed it 
would be found to be one of the highest interest: first, because 
during a total eclipse we are permitted a hasty glance at some of 
the secrets of nature which cannot be seen on any other occasion : 
secondly, because the general phznomenon is perhaps the most 
awfully grand which man can witness. Many of his audience had 
probably seen large partial eclipses of the sun, and they might sup- 
pose that a total eclipse is merely an intensified form of a partial 
eclipse; but, having himself witnessed a total eclipse, he was able 
to assure them that no degree of partial eclipse up to the last moment 
of the sun’s appearance gave the least idea of a total eclipse, as re- 
garded either the generally terrific appearances, or the singular 
nature of some of the phenomena. Many years ago, in reading the 
admirable essay in the Philosophical Transactions by the late Mr. 
Baily on the eclipse (usually called that of Thales), the occurrence 
of which suspended a battle between the Lydians and the Medes, he 
had been struck by the cogency of Mr. Baily’s arguments, which 
showed that only a ‘otal eclipse could be admitted as sufficient to 
produce the effect ascribed to it; and by the remark (cited by Mr. 
Baily) of Maclaurin and Lemonnier, that in an annular eclipse of 
the sun, even educated astronomers when viewing the sun (nearly 
covered by the moon,) with the naked eye could not tell that it was 
not full. The appearances, however, in a total eclipse, as he should 
afterwards mention, were so striking, that there could be no diffi- 
culty in believing the historian’s account to be literally correct. 
Proceeding first to explain the simple causes of a solar eclipse, the 
Lecturer remarked that the moon’s distance from the earth is nearly 
one four-hundredth part of the sun’s distance, and that the moon’s 
diameter is very nearly one four-hundredth part of the sun’s dia- 
meter, and that therefore, on the average, the sun’s apparent 
diameter and the moon’s apparent diameter are very nearly equal. 
But in consequence of the elliptic forms of their orbits, the sun’s 
