Q Examination of the Theory of a Resisting Medium. 
similar to the movement of fish in water.(2) The name by which 
it was known to them is akash; and Mr. Dow, in his dissertation 
| upon the religion of the Bramins, defines it to be ‘a celestial ele- 
ment, pure and impalpable, in which the planets move.” ‘This 
element,” he continues, ‘‘ according to Bedang, offers no resistance ; 
so that the planets have moved uninterruptedly therein, from their 
first impulsion which they received from the hand of Brama; and 
they will not be arrested until the moment when he shall seize them 
in the midst of their course.’”(3) The Chaldeans, also, held this 
opinion, and in the figurative language of the East were wont to 
represent the planets, including the sun, the earth and the moon, as 
vessels moving therein, and suited to such navigation.(4) Alhazen, 
an Arabian optician of the eleventh century, taught the existence of 
ether, which he designated ‘‘ the substance of heaven,” and he sup- 
posed it situated beyond, and differing in character from, our atmos- 
phere.(5) Tycho Brahe reinstated the ether of the ancients in all 
its rights. But though he regarded it as existent, he denied to it 
the power of causing refraction, which he attributed solely to the 
grosser vapours of our atmosphere. Whatever may be the difference 
in the natures of these two fluids, says he, the atmosphere so dimin- 
ishes in density upward, that at the point where it touches the ether 
it differs little from it.(6) Kepler, in following the crowd who had 
gone before him, revived this theory, in his day, and turned the 
substance in question to good account in framing some of the absurd 
theories which he put forth, along with his immortal: discoveries. 
In seeking the origin of comets, he supposed them native inhabit- 
ants of this ether, as fishes are of the waters of the earth; and that 
God created them to inhabit the immense spaces of the universe, 
as he did whales and other monsters to people the vast solitudes of 
the ocean. The sombre and bloody appearance which the sun 
sometimes exhibits he attributed to a coagulation of the ether; and 
when these appearances ceased, that result was produced by a col- 
lection of the grosser portions, which had disturbed its transparency, 
and their conversion into comets.(7) 
(2) Bailly, Histoire de  Astronomie Ancienne, p. 115. 
(3) Bailly, Traite de ’ Astronomie Indienne et Orientale, p.206. The work of 
Mr. Dow we have not seen. 
(4) Bailly, Histoire de ’Astronomie Ancienne, p. 139. 
(5) Bailly, Histoire de l’Astronomie Moderne, tome 1, p. 238. 
(6) Ibid. tome 1, p. 404. (7) Ibid. tome 2, p. 124. 
