28 o Dr. Herschei/s Observations to investigate 
opening, is now more abruptly terminated at the bottom of its 
thickness; the hanging or projecting clouds being removed 
towards the following side.* 
OF SHALLOWS. 
Shallows are depressed below the general Surface of the Sun ; and 
are Places where the luminous solar Clouds of the upper Regions 
are removed. 
That those appearances which have been called penumbrae 
are real depressions, or shallows, may already be concluded, 
from what has been related with regard to the slopes from the 
upper surface of the sun, down to the top of these shallows ; 
and will follow still more evidently, from an observation of one 
of them on the very limb of the sun. 
Dec. 3, 1800. There is a considerable opening just come into 
the disk, which is followed by another that is actually in the limb 
of the sun. The uniformity of the circular termination of the 
limb suffers a small deviation; it being somewhat depressed, 
owing to the shallow about the opening. Ido not yet perceive 
the opening itself with certainty ; but suppose it will appear to 
be one, when it advances more into the disk. 
The Thickness of the Shallows is visible. 
«■ 
Jan. 6 , 1801. There is a large opening much advanced be- 
yond the centre, with a shallow round it. On the preceding 
side of the shallow, its descent down towards the opening is 
visible; but, on the following side, I see abruptly into the 
opening. 
See Plate XIX. Fig. 12. 
