338 MR WILLIAM SWAN ON THE 
It is evident that if the telescope were mounted equatorially, the level could 
be dispensed with, and the objects might be referred to a parallel of declination, 
by causing a spot on the sun to travel along the wires; but my stand was too 
rude to allow this method to be adopted with safety.* 
In order to ascertain the times of the different phases of the eclipse, I used a 
box chronometer by ApAms of London, which was obligingly furnished by Lieute- 
nant Perrersson. It was compared with his standard chronometer about 3" 15™ 
before the commencement of the eclipse, and again the following day after an in- 
terval of 24 hours. The error and rate of the standard chronometer had been de- 
termined by observations made with a small transit instrument at the Observa- 
tory. 
For several days before the eclipse the weather was variable, with little sun- 
shine; and it became gradually worse, until at length the morning of the 28th 
arose as gloomy as the most unfavourable foreboding could have anticipated. 
But about noon, to the great delight of every one, the sun shone brilliantly, and 
the sky soon became nearly cloudless towards the zenith. This state of things, 
however, did not last long; for shortly after the commencement of the eclipse, an 
extremely thin cirrous cloud began to overspread the sky. I was apprehensive 
that this might interfere with the observation of the eclipse; but it produced no 
sensible effect in impairing the definition of the sun, which was remarkably good, 
and unusually free from tremulous motion. All the minute spots and faculz, 
which were visible before the cirrous cloud had formed, were seen until they were 
covered by the moon; and it was only after the total phase of the eclipse had 
passed that the definition was perceptibly injured. Towards the horizon, espe- 
cially in the east, the sky was pretty thickly studded with detached cumulous 
clouds; and a strong south-west breeze continued to blow during the eclipse, ex- 
cept about the period of the totality, when the wind almost entirely subsided. 
I determined the places of the only spots I saw near the sun’s limb by means 
of the position micrometer. There was a patch of small spots 96° 30’ to the west 
of the sun’s vertex, and about 1:5’ from its limb; and a considerable spot, evi- 
dently round, but much foreshortened, 62° to the east of the vertex, and less than 
1’ from the limb of the sun. This spot was surrounded by conspicuous faculee ; 
and after two days, when it had advanced on the sun’s disc, it proved, as it had 
seemed at first, to be circular. 
At the commencement of the eclipse, my eye was directed to the point at 
which the moon’s limb entered the sun’s disc; but, although I distinctly saw the 
first impression of the moon, I did not feel perfectly sure of this until about two 
* The chief inconvenience I found in using this instrument, arose from being obliged to point the 
telescope by the hand. A slow rack motion would have been very useful. In observing a total 
solar eclipse, every moment is so valuable, that too much care cannot be bestowed beforehand in 
having everything adapted to save time. From my own experience, I should recommend observers 
to have their telescope mountings as commodious and firm as possible. 

