The sun. [volume] (New York [N.Y.]) 1833-1916, 1882-12-17

be encountered by inc eHrtu DelOTo tuc ciHy
dust and gravel which formed the relatively solid
portions Of the tail. OF what do these gases
consst2 Tho experiments made by Padre
Secchi with the spectroscope on Winneckos
comet in 1868 render II almost certain that the
gas present in what we call the yellow hair OF
comet Is carburetted hydrogen. which. mixed
In certain proportions with tho atmospheric
afr. would produce the most appalling explo-
sions and con floss~t,oas. According thon. to
Mr. Donnelly's theory. the first effect OF tho
close approach Of the earth to the tail Of great
comet would be tho world-shaking noise OF
terrible explosions. accompanied by sheets OF
flame and an unearthly heat. under which
springs. ponds. lakes. and rivers would dis
appear as il by magic. while the original sur
face rocks underneath tho drift would be
decomposed and glazed. so to speak. as we
now find them. Then would come an
instantaneous descent OF granite dust
and gravel In masses sufficient to smash
and crush huge trees to the ground. TO
bury their trunks and cover the earth with
deposit from fifty to Ave hundred feet high. But
how. it may be asked. does this hypothesis ac-
count for the removal of great bouldcrs weigh
ing many tons for hundreds Of miles from their
original site? Mr. Donnelly meets this obiec-
tion by reminding us of the power exhibited by
the ordinary hurricanes Of the earth. wnicn
"fiooi thc ScSt IISCS tuTOW uluSSlNc
buildings. If we take into account. he says.
the excessive heat and electrical arrangements
that must have accompanied the drift age We
should have to multiply the hurricane of the
West Indies or the cyclone Of the Mississippi
valley II hundred or thousand fold. and we
should then. he submits. have power enough to
move all the rocks found scattered over the
face OF the drift deposits.
But let us return for moment to the au-
thor's conception of the consequences to
the Garth that would ensue from his con-
jectural collision. Ono effect. as we have
seen, of the great heat would be the
IMPORTATION of large part of the wa
tiers OF the globe. But no sooner would the
earth have passed through the trail Of the
comet than the heat engendered by contact
with the gas and debris would gradually begin
to be dissipated. Then the process Of conden-
sauon would set in. and pail OF dense cloud
many miles in thickness would enfold the
earth. The suns rays being shut out for
long period the earths surface would steadily
grow colder. and on all the uplnnds and coun-
tries distant from the equator tho pouring rain
would turn into snow. For weeks. months,
perhaps for years. the process of vaporiza-
ton and condensation would repeat itself.
the rains and SHOWS would go on fall
ing. and the few survivors OF the cataclysm.
p,ering forth from their refuge in mountain
caves. would pray. rs the legends of many
nations report them to have prayed. for the
homecoming Of the sun. But when the life
breodin. luminary once moro breaks through
the clouds. he looks upon wrecked and bar
rem earth the mild. eternal summer of tho ter
tary age is gone. From that day to this the
battle between the sun and the ice deposits OF
the high ATTITUDES has continued; the ice fields
and intolerable climate of tho poles represent
ing the residuum Of the refrigeration caused by
the evaporation due to the comets heat and
the long absence of the sun during the period
OF darkness. Every north wind brings us the
breath of the snow every south wind is part OF
tho suns contribution toward undoing the
comets work. 4 continual amoloraton Of
climate seems to have been going on since the
so-called glacial age. and the author OF this
book suggests that tho temperature of the
tertiary epoch represented tho true climate Of
the earth undsturbed by comet catastrophes-
n climate eQuabe. stormless. and warm.
More than half OF this volume Is occupied
with the results OF the inquiry how FAR the ex-
PLANTATION of the drift phenomena by collision
with comet is supported by the myths and
legends of various nations. Mr.. Donnelly un-
dertakes to show that the memory of great
confagration which once swept the earth is
preserved in the traditions Of the ancient Hin
docs. the ancient Persians. the Arabians. the
Greeks and Romans. the ancient Britons and
scandfnavians, the Toltccs and Aztecs OF Mex
leo. the ancient Peruvians and numerous
tribes Of Indians in North and South America.
An attompt is also made TO prove that the book
of Job and the book of Genesis can be intelli-
gibly interpreted in accordance with the comet
hypothesis, but with no other. Some Of the
evidence collected from myths and legends is
curious. and the reader will find this portion
OF the book extremely interesting; but we do
not here dwell on it, because if Mr. Donnclys
theory could be established. or made to appear
probable. on scientific grounds, we should ex
pect tradition to preserve some traces Of tre-
mcndous catastrophe which. if it occurred at
all, must have taken place scarcely more than
10000 years ago-that is TO say. long after the
human race can be proved to have inhabited
the earth.
To recur. then, for moment to the sccn-
tnc side OF the inquiry is there anything
incredible even surprising in the
hypothesis that n comet might have struck
the earth in the remote past2 Is it not
rather marvel rs Mr.. Donnelly suG-
gcsts that the earth should escape collision for
n single century? kcpler affirmed that comets
are scattered through the heavens with as
much profuson as are fishes in the ocean. Arago
estimated that the comets belonging to the
lar system within the orbit OF Neptune num-
bered II 500 900. Lambert regards 100000
600 rs very moderate estimate. These COM
putations. moreover. do not include the fiery
wanderers who may at any moment visit us
from outside the solar system. But how many
Of these comets come near the orbit Of the
earth? 1t is certain that some actually inter-
sect its orbit while others approach it very
closely. In the former category may be men
toned Gambart's comet, Brorsen's comet
Enckes comet. Hallcy's comet. The comet
discovered Oct. 10. 1880 by Louis
Swift of Rochester. N. Y. was only
distant from the earth about one-tcnth
of one per cent. OF the distance of the earth
from the sun. The new comet discovered
June %, 1881 was at its nearest point distant
less than one third Of one per cent. OF the dis
lance of tho sun from the earth. In the year
1873 IeXells comet approached tho earth SO
closely that it would have increased the length
Of the sidereul year by three hours if its mass
had been equal to the earths. This same
comet did actually strike our fellow planet
Jupiter or. at ali events, became SO cntansed
among Jupitcr's satellites as to lose its orig
inal orbit Not one Of the satellites altered its
movements a hairs breadth. but it must be re-
memberel that We had then and have now no