
Sept. 14,1871] 
_ Hence by formula (a) :— 

a hy Pxseoase ane 128°77 
ae & x 0.048544 x 0 0807288 & X 0°0039189 
SL a/ 32859 
— i . 
Orv= seuzie feet per second. 
k 
Assuming % = 1°3,* we obtain, 
v = 158°99 ( = 159) feet per second, as the maximum 
velocity attained by such a stone in falling to the earth. This 
velocity does not exceed one-tenth of the initial velocity of 
a rifle bullet. And, as the penetrating power of a given pro- 
jectile is proportional to the sgwave of its velocity, its power of 
penetrating the ice would only be one-hundredth part as 
great as that of a projectile of similar mass and dimensions 
moving at the rate of a rifle bullet. Hence we need not be 
surprised that the ice was not penetrated more than three or four 
inches. 
If the same mass of stone (two pounds) were sf/evica/ in form 
instead of czdica/, its diameter would be 3°2803 inches = 0'27336 
feet, and 4 = 0058689 square feet. In this case, we may 
assume £=0°7+ Hence, by the formula (a), we obtain, 
uv = 197°05 feet per second: so that in this case like- 
wise its velocity would be quite low, and its penetrating 
power very znsignificant. 
Of course, in the case of /axge meteoric stones the value of w 
would be much greater. Joun LE Conre 



ASTRONOMY 
The Solar Eclipse of 1868 + 
ADEN was chosen as the observing-station because from the 
general nature of its climate it was thought that a satis- 
factory view of the phenomena that took place during the 
eclipse might fairly be expected, and also because, as it was far 
removed from the stations of the French and English expeditions, 
any observations taken there would prove of considerable im- 
portance. The observers were Prof. Edmund Weiss (the leader) 
Prof. Oppolzer, and J. Rziha, already known for his observa- 
tions of the eclipse of 1867. 
On the morning of the eclipse (Aug. 17) the state of the 
atmosphere proved unfortunately anything but favourable for 
astronomical investigation, owing to the presence of a great 
amount of cloudiness. According to Oppolzer the beginning 
of the totality was 184 29™ 30°°0 (Aden mean time), the end 
18h 33™ 245 6, 
A few moments before the total disappearance of the sun, 
Weiss saw on it a beautiful carmine red border or streak, in the 
middle of which arose a similarly-coloured complicated promi- 
nence (No. 1) which lasted for a few seconds. Half a minute 
later (18" 3025) a second prominence (No. 2) appeared, long, 
thin, and in shape resembling a slightly bent finger ; nearly two 
minutes later (18" 31™ 58s) he noticed a third smaller, hill- 
shaped, or conical prominence (No, 3). Just at the end of the 
totality another beautiful red border appeared, on the outer edge 
of which was a gleam of deep blue, most intense at the point of 
junction with the red, and rapidly fading away on the outside 
into the background. 
Some English officers stationed a short way off also noticed 
the first two prominences (which they say were visible to the 
naked eye) and the red border at the end of the totality, but 
they failed to see prominence No. 3, perhaps for want of suffi- 
cien!ly powerful or properly adapted instruments. 
Oppolzer’s observations coincided with those of Weiss, except 
that he failed to see prominence No. 3 on account of the inter- 
ference of passing clouds, though he suspected its presence irom 
a certain 1ed appearance at the spot indicated by Weiss. Satis- 
factory observations of the corona were rendered impossible by 
the state of the atmosphere. 
* For cubes moving in water the experiments of Du Buat and Duchemin 
give & = 1'28., : " é 
+ For spheres moving in airy the experiments of Robins and Hutton give for 
velocities :— 
@ = 3°28, 1674, 82, 328 feet per second. 
& = 0°59, 0°63, 0°67, 0°71. 
t Astronomische Nachrichten, No. 1836-1837: ‘‘ Account of the observa- 
tions of the Austrian Expedition sent to Aden to watch the total solar 
eclipse of 1868.” 
NATURE 

509 

Rziha’s part was confined to the spectrum, and his account is 
that simultaneously with the disappearance of the last sunbeam. 
Fraunhofer’s lines entirely vanished, the spectrum became con- 
tinuous and remained so to the end of the totality. All his 
efforts to detect any reversal of the lines proved ineffectual. 
Just before the reappearance of the sun, thin clouds intervened 
and hid the greater part of the corona, so that the principal 
sources of light were the red border and the prominences. At 
this moment the more refrangible rays from the green disappeared 
gradually, and only the red end of the spectrum remained, con- 
sisting of deep red, carmine, orange, feeble yellow, and the 
faintest possible tinge of green, at the same time this remaining 
part became discontinuous owing to the appearance of dark 
lines in it, which did not, however, coincide with any of the 
principal lines of the ordinary spectrum. The disappearance of 
the dark lines, Rziha seems to think, would connect the corona 
with a solar atmosphere ; and he suggests that the lines or streaks 
which appeared afterwards were due to absorption by the water- 
vapour of our own atmosphere, 

PHYSICS 
On a Quantitative Method of Testing a “ Telegraph 
Earth,” by W. E. Ayrton* 
THE method used up to the present time for testing a tele= 
graph earth has been gualitative only. As, however, the 
electrical condition of every ‘‘earth” is of great practical ims 
portance, it is necessary that some accurate guavttitative method 
should be devised, in order that every telegraph office may 
ascertain whether the resistance of their earth is higher or lower 
than the maximum resistance allowed. The principal difficulty 
met with is that, if the resistance between two earths be measured 
successively with positive and negative currents, the same result 
is not obtained. Consequently the ordinary law for a Wheat- 
stone’s Bridge, or Differential Galvanometer, would not hold 
true. This difficulty, however, has been overcome in this paper, 
and formulze are developed suitable for a Wheatstone’s Bridge, 
a Differential Galvanometer, or a Galvanometer of which the 
law of the deflections is known. 
The details of some experiments are also given, and a par- 
ticular instance is mentioned in which a much better ‘‘ earth” 
was obtained by burying the plate in the upper stratum of soil 
than by burying it much deeper, on account of a bed of sandstone 
that existed at about fifteen feet below the surface. 


SCIENTIFIC SERIALS 
THE American Naturalist for September commences with an 
article by Mr. W. J. Hays, entitled ‘‘ Notes on the range of 
some of the Animals in America at the time of the arrival of the 
white men.” The moose, now almost entirely driven out of the 
United States, was, at the time of the first European settlement, 
found as far south as New York city ; the range of the carriboo 
was not more extensive then than it is now, although fossil re- 
mains have been found as far south as the Ohio; the musk-ox is 
not mentioned by the early travellers; but the common deer 
(Cervus virgineanus and C. campestris) was everywhere repre- 
sented as existing in incredible numbers. The Wapiti deer was 
found all along the coast from Canada to the Gult of Mexico 3 
the bison (improperly called the buffalo by the early settlers), 
also ranged along the coast from the valley of the Connecticut to 
Florida, and roamed over the entire country now known as the 
United States, and extending as far north as the sixtieth parallel 
in British America. Mr, Hays reckons that at the present time 
not fewer than half-a-million bisons are annually de-troyed ly 
the hand of man. The red fox existed in America before the 
advent of the white man, in addition to the gray species, notwith- 
standing assertions to the contrary; wolves were everywhicre 
abundant, as also was the beaver; the jaguar, not now found 
east of Texas, occurred in the mountains of North Carolina as 
recently as 1737 ; the dog was found in all parts of the country ; 
and, from the descriptions, must have been of the same species 
as those now found with the Indians of the plain. The only other 
original article in the number is ‘‘()n the Food and Habits of 
some of our Marine Fishes” by Prof. A. E. Verrill. 
THE most important paper in the Fournal of Botany for Sep- 
tember is an article by Mr J. G. Baker ‘On the Dispersion of 
Montane Plants over the Hills of the North of England.” Mr, 
* From the Proceedings of the Asiatic Society of Bengal, 
