PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
85 
Another sub-kingdom was that of the Mollusca, which 
included, in addition to slugs, snails, whelks, oysters, 
cuttlefish, &c., the various sea-mats and their allies. 
After briefly alluding to the sub-kingdoms Echinoder- 
mata and Vermes, the author passed on to the Arthropoda, 
which contains all the animals without backbones, and 
which have legs with joints. To this sub-kingdom belonged 
all the insects; crabs, lobsters, and other shell-fish; scor¬ 
pions, spiders, mites, &c.; and as many of the animals be¬ 
longing to it were terrestrial, and hence represented in our 
own district, more space had been allotted to it than to some 
of the other sub-kingdoms. In the latter part of the paper 
the various orders of insects were enumerated and described. 
The author reserved for another occasion his remarks as 
to the typical collection illustrative of the backboned or 
vertebrate animals, as well as the botanical type collection. 
December 7th, 1882. 
Dr Buchanan White, E.L.S., in the Chair. 
NEW MEMBERS. 
The following new members, proposed at last meeting, 
were unanimously elected :—Mr Alex. Menzies, Hector of 
Kirriemuir Seminaries; Mr W. Cochrane Young, solicitor, 
Perth; Mr James Thomson, C.E., Edinburgh; Mr C. S. 
France, Balboughty; Mr Athole M'Gregor, Eastwood, 
Dunkeld; andDrCalder, Perth. Dr James Croll, F.R.S., 
was elected an honorary member. Mr Samuel L. Condall, 
Perth; and Mr Robert Keay, Assistant City-Clerk, were 
nominated for election as ordinary members. 
DONATIONS. 
The following donations were intimated :—Perthshire 
Collection. Insects, from Mr John Stewart, Mr John 
Bruce, Mr P. D. Malloch, and Mr George Alexander; 
and a large number of plants, from Mr C. MTntosh, 
Inver. Index Collection. Zoological specimens, from Mr 
P. D. Malloch. 
Mr James Stewart presented a disarticulated skeleton 
of a bird to the Society, and exhibited the skeleton of a 
mole, and explained the structure. 
“PROCEEDINGS.” 
Part II. of the Society’s Proceedings and the catalogue 
of the books in the Library were laid on the table. 
The following paper was read:— 
“ Light .” By Thomas Miller, LL.D., F.R.S.E., Rector 
Emeritus of Perth Academy. 
The sun might be considered the sole source of light and 
heat, and indeed of all physical change in our system except 
the tide of the ocean, of which the attraction of the moon 
was the principal cause, but even in that the sun had a 
considerable influence, while the amount of light and heat 
which it diffused through space was great beyond concep¬ 
tion, and the intensity of its light was exceedingly great. 
The sun gave as much light as 146 lime-lights, and the 
earth intercepted only a small portion of it and the sun’s 
heat. The dissipation of energy in the case of the sun 
was prodigious, and the portion intercepted by the earth 
was sufficient to melt annually a shell of ice 30 metres, or 
105 feet, thick, surrounding its whole surface. As to the 
restoration of the sun’s energy, the author shewed that it 
could not be by combustion, and afterwards spoke of the 
meteoric hypothesis, in connection with which he gave some 
very interesting calculations, from which it appeared that if 
there were a sufficient number of meteors in the vicinity 
of the sun, these would maintain its heat and light by 
continually impinging on its surface, while its increase in 
magnitude would be so small that we could not detect it by 
even our finest instruments, although this process were to 
go on for 4000 years. But that there was not the neces¬ 
sary number of meteors near the surface of the sun was 
proved from the circumstance that comets approached 
very near it in their perihelion passages, and the move¬ 
ments in their orbits were not in any degree affected. 
It being therefore obvious that the fall of meteors could not 
account for the phenomena, they were compelled to have 
recourse to the hypothesis of Sir William Herschell and 
La Place, viz., that the solar system existed at one time as 
a vast nebula; that it gradually contracted by the force of 
gravitation, and in doing so evolved much heat and light; 
that this nebula had a revolution on its axis from west to 
east, and that it threw off by its centrifugal force various 
rings, which afterwards formed the planets Neptune, 
Uranus, Saturn, and Jupiter; that the ring between Jupiter 
and Mars, having had no preponderating mass in any part 
of it, broke up into a vast number of small bodies called 
planetoids, such as Vesta, Juno, Ceres, Pallas, &c.; that 
the next ring produced Mars, the next the earth, the next 
Venus, and the last Mercury; that the satellites were 
similarly formed; that all these existed during unfathom¬ 
able ages in a state of intense incandescence, many times 
hotter than iron at a white heat; that the satellites, 
being comparatively small bodies, cooled first, and 
