212 
NATURE 
[Fuly 14, 1870 
and the brilliancy of any orb, its ‘‘magnitude” in fact, will 
therefore depend on its age, quite as much as on its size or dis- 
tance. On this view, Sir W. Herschel’s method of ‘star gaug- 
ing” cannot be relied on for a correct determination of tne actual 
shape of the cluster called the ‘‘ Milky Way,” as instead of 
taking the average of brightness only, as an indication of the 
average of distance, we have to superadd the average of age. 
Now, the smaller the star, the more quickly will its light die out, 
and, therefore, the necessary extent of our galaxy is immensely 
reduced ; in other words, it appears that while the space separat- 
ing us from the nearer stars, for which parallax has been obtained, 
remains of course unchanged, the computed distances of those 
hitherto considered to be farthest off, will be much lessened, as 
there appears to be no reason for concluding that telescopic stars 
are necessarily more distant than brizht ones for which we 
cannot obtain parallax, but simply that they are older, or smaller, 
or both, and therefore dimmer. 
Mr. Proctor, in ‘‘ Other Worlds than Ours,” argues that-as 
telescopes barely reach the outermost stars of our own cluster, 
therefore it is impossible that they should reach to and resolve 
clusters constituting other systems and lying at distances enor- 
mously greater, and therefore that the resolvable nebulze must lie 
within our galaxy. If my idea that the stars of our cluster 
which the telescope shows with difficulty, are not distant but 
dim, be correct, Mr. Proctor’s argument appears to lose its 
force. 
It will be readily allowed that if the light of the stars be fad- 
ing away, a vast number may have already become extinct, and 
that it is indeed possible that the orbs now visible may be but a 
small surviving remnant of far greater multitudes which once 
illumined the heavens. If our cluster then be much reduced in 
extent, and its constituents be largely increased in number, it 
would follow, I imagine, that the chances against collision would 
be much reduced, and it then becomes less difficult to conceive 
the possibility of such an event having occurred in the case of 
the recent outbreak in 7+ Coronz Borealis, especially if it were 
caused by the unobserved approach of an extinct body. This 
outbreak is usually ascribed to a sudden conflagration of hydrogen, 
the star being, as Prof. Roscoe says, ‘‘on fire.” But a star self- 
luminous surely must be always on fire, and if it contain hydro- 
gen, that gas must be in a state of constant conflagration. The 
temporary brilliancy of the star seems rather such as would be 
occasioned by a collision with some comparatively small body, 
whose impact was yet sufficient to generate heat enough to ac- 
complish its own disintegration and ignition, Let us suppose 
that collisions are possible, and that their frequency is merely a 
question of the chances. What would be the consequences of 
such an event? I imagine that they would depend chiefly on 
the relative momenta of the colliding bodies; that if one were 
very much larger than the other, and the velocities high, the tem- 
perature would be raised sufficiently to dissipate the smaller into 
gas, while merely heating, or possibly liquetying the larger. If 
the bodies were nearly of a size, and their momenta were great, 
possibly both would be reduced to a gaseous condition ; in either 
case their tendency would be to form ultimately a body equal in 
weight to the sum of its two constituents. ither the larger 
body would annex the smaller, or, if both became nebulous, the 
fervid gases would radiate their heat and contract anew into 
a system possibly containing a sun and planets. 
Again, supposing that two bodies approach each other in such 
a manner as to avoid a collision, that is, so that their mutual 
vravity causes them to leave their paths and revolve round each 
other, we should have the explanation of the existence of double, 
treble, multiple stars; we should also understand how it happens 
that some stars (Sirius, for instance,) are accompanied by non- 
luminous orbs. Also, it would seem that if extinct stars are 
really far more numerous than is generally supposed, the theory 
which regards the revolution of attendant dark bodies as one 
cause of the variability of certain stars, receives fresh support. 
Thus, in the course of time, nebulee would form suns, suns 
would grow cold, or, while yet glowing, would come into con- 
tact and combine with other suns, till gradually space would be 
peopted with suns, larger and larger, but less and less thickly 
strewn, Pursuing the idea, we arrive at a period when all the 
stars of cach galaxy shall become agglomerated into one mighty 
. globe—nay, when all these vast galactic suns shall come together 
and form one solitary orb, in which all the matter once scattered 
through space shall be collected, accomplishing its suczessive 
fates as a sun without a system—a world without a sun—a cold 
and naked ball. EARDLEY MAITLAND 
Why is the Horse Chestnut Tree so called ? 
DuRInc the spring this tree is the ornament and pride of our 
public and private parks. In ‘‘ Woodland Gleanings ” it is stated 
to be a native of the north of India, and is supposed to have been 
introduced into England about 1575. 
Our observant forefathers have given it the very significant 
name of Horse Chestnut (Castanea Caballina),* to distinguish it 
from all other species of chestnuts. The 7¢ason for so doing I 
have never seen stated in print ; but from the three specimens ot 
cuttings from a branch of this tree which I enclose, it will be very 
manifest. All over its branches, at every bud, can be seen what 
at a glance will be taken for an exact conformation of the foot of 
@ horse, exhibiting the hoof, the nails of the shoeing, the fetlock- 
joint, &c., in marvellous miniature, some, of course, better de- 
veloped than others. This curious freak in nature’s vegetable 
kingdom, has, no doubt, been the origin of our nomenclature 
of this tree ; and it would be an interesting point of philological 
inquiry to ascertain wh ther or not its native Asiatic name has 
incorporated or associated with it that of the horse ? 
I write with the view of eliciting information on this point, and 
with the hope, too, that some of your botanical contributors 
will throw further light on this peculiarity. 
EUGENE A, CONNELL 
Fall of an Aerolite 
A LETTER of the year 1628, ‘‘sent by Mr. John Hoskins, dwell- 
ing at Wantage, in Berkshire, to his son-in-law, Mr. Dawson, a 
gunsmith dwelling in the Minories without Aldgate,” and pre- 
served among Nehemiah Wallington’s Historical Notices (i. 13) 
contains the following narration :— 
“©On Wednesday before Easter, being the ninth of April, about 
six of the clock, in the afternoon, there was sucha noise in the air, 
and after such a strange manner, as the oldest man alive neyer 
heard the like. And it began as followeth :—First, as it were, 
one piece of ordnance went off alone. Then after that, a little 
distance, two more, and then they went as thick as ever I heard 
a volley of shot in all my life; and after that, as if it were the 
sound of a drum, to the amazement of me, your mother, and a 
hundred more besides ; yet this was not all, but, as it is reported, 
there fell divers stones, but two is certain, in our knowledge. The 
one fell at Chalows, half a mile off, and the other at Barking, 
five miles off. Your mother was at the place where one of them 
fell knee deep, till it came at the very rock, and when it cameat 
the hard rock it broke, and being weighed, all the pieces together, 
they weighed six-and-twenty pound. The other that was taken 
up in the other place weighed half a tod, 14 pound.” 
I do not know whether there may be any other record of this 
remarkable aerolite, so. simply but graphically described. Is it 
not just possible that some of the fragments may yet be preserved 
in the neighbourhood of its fall? At any rate a search would 
involve but little trouble. T. W. WeEzB 
ANDERSON’S UNIVERSITY 
WE extract the following from the Zvening Citizzn (Glas- 
gow) of June 22 :— 
‘*The annual meeting of the trustees of Anderson’s Uni- 
versity was held this afternoon within the institution. Mr, 
William Ewing, in the absence of the president, was called to 
the chair. In the annual report which was submitted, reference 
was made to the death of Dr. Penny in November last, and the 
appointment of a successor. Mr. Young, of Kelly, who had 
arranged to set aside 10,009 guineas for the endowment of a 
Chair of Technical Chemistry in connection with the University, 
had, it was stated, no further proposal to make, he leaving it to 
the trustees to make what alteration in the deed of trust they 
may think proper. Under these circumstances, the managers 
recommended that advertisements be issued for a successor to 
Dr. Penny ; that the chair should in future be styled the Chair 
of Scientific Chemistry ; and that in electing the professor power 
should be reserved to the trustees to create such other chair or 
chairs of Chemistry in connection with the University, and elect 
such additional professor or professors to fill said chairs as the 
trustees may see fit ; and also to arrange and define, from time to 
time, the respective departments of the subject to which each 
professor, including the Professor of Scientific Chemistry, should 
devote himself. Regarding the mode of electing professors, the 
* The scientific name of the horse-chestnut is Asculus hippocastanum 
it has no relationship to the Castanea, or sweet chestnut.—{Eb.] 
