34 
often interrupted by the breakage of the wire rope; for this 
purpose two engines are used, one at cach end of the tunnel, 
while the obvious and ordinary arrangement would he to employ 
only one engine driving a shaft with two drums and an endless 
rope. ‘Che arrangements might be very similar to those adopted in 
mines for raising and lowering the “‘cage,"” except that in this case 
the cage would be the carriage, and would travel on nearly a level 
line instead of up and down ashaft. The mode adopted for rais- 
ing and lowering passengers in the shafts attached to the subway is 
by means of a chain which draws the carriage up and down, 
various ‘‘safety”’ arrangements being adopted in case of the 
giving way of the chain. For raising and lowering passengers, 
a chain or rope is not however the best means. In the apparatus 
in use in all the best hotels in America, there are no chains or 
ropes, no catches, springs, or buffers in case of accident. There 
is a vertical hollow cast-iron column reaching through the whole 
length of the shaft ; in that shaft is the thread or helix of a screw 
projecting a couple of inches from its surface; the cage forms 
part of the nut, which rests in the serew or shaft. The shaft 
is turned by asmall engine, controlled by the guard, who travels 
with the cage; he can moderate, stop, or reverse the motion, 
and accidents in the ordinary sense are out of the question. 
Tt will thus be seen that the problems to be solved as to the best 
means of transporting passengers through the Tower Subway 
are of the simplest kind. 
We understand that the late Mrs. Appold has left to the 
Institution~ of Civil Engineers, a lezacy of 1,099/., payable 
at the same time as the legacy for a similar amount from her 
husband, the late Mr J. G. Appold, F.R.S., Assoc. Inst. C.E. 
It is believed that both bequests have been made “for the 
general use and benefit of the Society,’ without being fettered 
with any conditions. 
To those of our Scientific Societies who annually assure them- 
selves, and others, of their continued existence by a dinner, we 
commend the ‘‘ Report of the Speeches ‘at the Annual Dinner 
of the Institution of Civil Ingineers, May 4, 1870,” which we 
have just received,—as an indication of what a little energy can 
make even of a dinner. Professor Tyndall answered for 
Science, showing in a clear way how physical research lies at the 
root of all conquests of Nature, gaining help in turn from the 
practical man. “ Thus does the human intelligence oscillate 
between sound theory and sound practice, gaining by every 
contact with each an accession of strength. 
are the soul and body of science, as far as you and I are 
connected with it. Sever sound theory from sound practice, and 
both die of atrophy. The one becomes a ghost, and the other 
becomes a corpse.” 
WE have received the first and second volumes of Dr. L. 
Lindenschmit’s ‘‘Die Alterthiimer unserer heidnischen Vorzeit,”’ 
from originals in public and private collections, published under 
the authority of the Roman-German Central-museum at Mayence. 
The illustrations are most copious, and the work admirably done. 
Dr. R. Cespary reprints from the Transactions of the Natur: 1 
History Society of Halle a paper on the genus Vuphar. In 
examining the water-lilies of the Black Forest, as well as of 
Prussia and other districts of Northern Europe, he finds an inter- 
mediate form between Wauphar luteum and N. pumilum, which 
he regards as a true natural hybrid between two distinct species, 
and not as a mere transitional form. Another reprint from the 
Transactions of the same socicty is an essay on the Lennoacee, 
by H. Graf zu Solms- Laubach. 
Koner’s Zeitschrift der Gesellschaft fiir Erdhunde za Berlin 
contains « number of most valuable geographical papers, acecm- 
panied with carefully-executed maps; and a list of all geo- 
graphical works, maps, and plans in all languages published 
etween December 1868 ant November 1869. 
These two things | 
NATURE 
[May 12, 1870 
THE PHYSICAL CONSTITUTION OF THE SUN 
RK. GOULD has addressed an important letter on the above © 
subject to the Journal of the Frankland Institute. In the 
first part he refers to the new light recently thrown on the sun’s 
physical constitution by the observations of Mr. Lockyer, and. 
agrees with him and Dr. Frankland, both as to the absorption 
taking place in the chromosphere and photosphere itself, and 
also as to the possible telluric origin of the corona. 
He then proceeds with regard to the probable age of the sun :— 
“The researches of Helmholtz and Thomson regarding the 
age of the sun as a source of cosmical heat have shown us limits 
within which, in the absence of more decisive evidence, we must 
restrict our theories as to the length of time during which he has 
warmed the earth. ‘The contraction-theory has been most ably 
discussed by these eminent physicists, and seems to afford the 
only satisfactory mode of accounting for the solar light and heat, 
now that we know both that the meteors generally revolve in 
cometary orbits, and that the habitability of the earth, as well as 
the apparent unchanged mutual attraction of the planets, bears : 
testimony to the incorrectness of the meteoric theory, From 
Pouillet’s data (derived from experiments which ought to be 
| repeated in some year when the solar spots are at a minimum) 
Helmholtz has shown that, even were the sun’s density uniform, 
a contraction of 4; per cent. in his diameter would evolve 
20,000 times the present annual supply of solar heat. But when 
the sun was hotter the same proportional contraction would have 
evolved yet more heat ; so that we must consider the above 
estimate as a minimum. 
‘The expansibility of hydrogen gas for 100° C. is 0°3661. No 
gas appears to have so small a coefficient as 0°360, which would 
correspond to a linear expansion of o°108. ‘The expansibility of 
glass, the smallest known, I believe, even for a solid, is about 
ity part as great ; say 0°09244 in volume, or O'coo8r linear, 
‘Lherefore for glass even, a contraction of I per cent. in diameter 
would imply a fall of temperature by 1230° C., and a mean spe- 
cific heat of 218. his seems certainly a minimum value. 
“But if we suppose the expansion coefficient to be as 
large as that of hydrogen, a contraction of I per cent. would 
correspond to a change of temperature by 8°2° C. or a mean 
specific heat of 32,700, if equivalent to 20,000 years’ supply. 
‘This is out of the question. 
“Now Thomson has computed that bodies smaller than the 
sun, falling from a state of relative rest at mutual distances which 
are Jarge in comparison with their diameters, and forming a globe 
equal to the sun, would generate 20,000 times the present annual 
supply. This would be greater did we consider the unquestion- 
able increase of the sun’s density towards his centre. And since 
it seems out of the question that resistance and previous minor 
impacts could have consumed more than one-half the heat, he 
one hundred million times to be the highest, estimate of the sun’s. 
initial heat. 
‘* Now we have every reason for the belief that radiation is pro- 
portional to temperature. Assuming this and taking the tempe- 
rature of the sun’s photosphere as 14,000° C., 
10,009,006 times the present annual supply would be radiated 
in 3,650,009 years if the specific heat were 218, 
in 7,280,000 ” ” ” ” 1000. 
100,009,000 times the present annual supply would be tadiated 
in 8,250,000 years if the specific heat were 215, 
in 25,500,000, ,, is = i“ 1000, 
500,000,000 times the present annual supply would be radiated 
in 11,700,090 years if the specific heat were 218, 
in 35,990,000 5, 5, 53 1000. 
“For vapours, other than hydrogen, the greatest known specific 
heat, so far as I am aware, is 0°508 (ammonia) ; and hydrogen, 
which has less than 3°5, cannot form any considerable portion 
of the sun’s mass.* A specific heat so high as 1,000 seems 
altogether out of the question ; yet it will be seen that, even on 
this supposition, an amount of initial heat equal to 500,000,000 
the present annual supply, would have been radiated in less than 
forty million years, were the sun’s radiative capacity pro- 
portional to his temperature. Taking the more probable age, - 
10,000,000 years, we should find 226 million times the pre- 
sent annual supply to have been radiated within this period 
if the specific heat were not greater than 218;. and even 
were the specific heat 1,°00, the total radiation would have 
been eighteen million times a year’s radiation at present. 
* It seems to form certainly not more than the 18,cooth part of the mass of 
the earth, 
inferred ten million times a year’s supply to be the lowest, and 
