
(503°) 
-XXXIV.—On the Total Solar Eclipse of 1851. By Professor C. Prazzi Smyta. 
(Read December 1, 1851.) 
~ Eclipses are still, as they have ever been, very important phenomena for the 
astronomical observer; partly on account of the crucial test which they afford 
for the examination of the truth of the theory and calculation of the motions, real 
and apparent, of the Sun and Moon, partly also for the special opportunities 
which they furnish of inquiring into some of the arcana of the physical charac- 
teristics of those bodies. 
-For the former purpose, a partial eclipse will serve almost as well as a total 
one; while the continued improvement of the observation of meridian passages 
is now raising these daily measures fully to the importance of the other occasional 
phenomena, as a test of the theory. But for inquiry into the physics of the Sun, 
a perfectly total eclipse of that body is necessary ; revelations may then happily 
‘be procured, which no observation of any other phenomena at any other time, can 
hope to afford any suspicion of. 
As the occurrence however of a total eclipse near any inhabited and civilised 
“region of the earth, is very rare; and as even when it does occur, the observation 
lasts but for three short minutes,—the utmost extremity of importance attaches 
to. the occasion in the eyes of all practical astronomers. So many circumstances, 
too, have to be noted, observed, and measured, within a’ few seconds, that it is 
“necessary to adopt some systematic division of labour amongst a number of ob- 
“servers, and for each to be previously practised and expert in his particular part. 
Much of this arrangement was organised for the eclipse of July 28, 1851; and 
while other observers were distributing themselves along various parts of the line 
of totality, I gladly seized the opportunity of occupying, in company with the 
Rey. T. R. Rozryson, D.D., the western coast of Norway, where the path of the 
*rtiinn’s shadow first entered Europe. On the importance of the occasion being 
3 “represented to the Commissioners of Northern Lighthouses, then sitting in Edin- 
burgh, that Board, who can so well appreciate science, and who have introduced 
“80 many of its more recondite appliances into their admirable establishments on 
the coasts of Scotland,—finding that their steam-vessel, the Pharos, would be 
ngaged amonest the Shetland Isles about the time of the eclipse, most liberally 
Mahidertock to convey Dr Roxrnson and myself to the selected part of the Nor- 
_ Wegian coast; a boon of so much the more importance, as that portion was un- 
visited, so far as we could learn, by any sort of vessels available to ordinary 
ae 
Being taken across the North Sea, then, in this manner, and having been pro- 
VOL. XX. PART III. — 6uU 
