282 Dr. Herschel’s Observations to investigate 
about D, that it appears as if it had not come from the opening 
C. The shallow A now ends in a sharp point.* 
i2 h 50'. The shape of the shallow A is again much changed ; 
it is no longer pointed, but very broad at the endrf- and there 
is a new branch breaking out at G. These changes seem all to 
denote, that the shallows are occasioned by something coming 
out of the openings, which, by its propelling motion, drives 
away the luminous clouds from the place where it meets with 
the least resistance ; or which, by its nature, dissolves them as 
it comes up to them. If it be an elastic gas, its levity must be 
such as to make it ascend through the inferior region of the 
solar clouds, and diffuse itself among the superior luminous 
matter. 
i h 10'. The new branch G increases ; and the openings C, D, E, 
are enlarged. A new branch is also breaking out from the shal- 
low about E. It is marked H in Fig. 14, and denoted with points. 
These changes seem to prove, that the same gas which diffuses 
itself over the shallows has forced open the passages at first, 
and is now widening them. Hence, the increase of the open- 
ings is an additional circumstance which points out the cause of 
the shallows. 
i h 20'. From the shallow of a very large preceding opening, 
which is in an increasing state, are lately projected three small 
branches a, b, c. J 
2 h 30'. The vacancies between the three small projecting 
shallows are now filled up by the same cause that occasioned 
them, so as to have given them the shape of an uniform but 
broader shallow, on the side where the branches come out, as 
denoted by points. 
* See Plate XIX. Fig. 15. 
f Fig. 16. 
t Fig. 17. 
