198 
CONSTRUCTION OF COMETS, &C. 
helion dis- 
tance 
consists also of the condensation of seme remaining phosphoric 
matter/ suspended in the lower regions, of an elastic, trans- 
parent fluid, extending probably far beyond the cbevelure 
without our being able to perceive it. 
The faintness We might ascribe the little extent and extreme faintness of 
not arise*frt)m ta ‘* to the great perihelion distance of the comet, if it had 
its great peri- not already been proved, by the comparative view which in 
my last paper has been taken of the two comets of 1807 and 
1811, that the effect of the solar agency depends entirely upon 
the state of the nebulous matter, which the comet in its ap- 
proach exposes to the action of the sun. Oar last comet 
therefore had probably but little unperi he Honed matter in its 
atmosphere. 
Other proofs The high consolidation of the matter contained in the second 
ot (he high comet is also much supported by the different appearance of* 
Consolidation . 11 7 
of this comet. the two comets in the observation of the 9d of January. In 
order to judge of them properly, we must consider their situa- 
tion with regard to the sun and the earth $ the first comet was 
| §2 millions of miles from the sun ; the second only 1 64 : the 
first was at the same time 262 millions from the earth : the 
.econd only 83 j but, notwithstanding the great disadvantage 
of being 28 millions of miles farther from ‘the sun, anchabout 
J70 millions farther from the earth, the first comet had the 
luminous appearance of a brilliant head accompanied by a tail 
45 millions of miles in length ; whereas the second comet, so 
advantageouly situated, had only a very faint cbevelure about 
its large but faint nucleus, with a still fainter tail, whose length 
has been shown not much to exceed half a million. 
Jiesplts. if then the effect of the action of the sun on the comets at 
the time of their perihelion passage is more or less conspicu- 
ous, according to the quantity of unperihelioned nebulous 
piatter they contain, we may by observation of cometic phe- 
nomena ^arrange these celestial bodies into a certain order of 
consolidation, from which, in the end, a considerable insight 
into their nature and destination may be obtained. The three 
last observed comets, for instance, will give us already the 
following results. 
This comet I he comet of which this paper contains observations, is of 
would nave SDC h construction that it was but little more affected by a 
been not more 7 
affected than perihelion passage than a planet would have been. This may 
be 
