i88i.] 
55 1 * 
Analyses of Boohs . 
whites, and for a short time perhaps capable of less powerful 
exertion, but they possess extraordinary powers of endurance, 
and in the long run would easily outstrip the whites.” They are 
likewise, in opposition to another current nation, decidedly pro- 
lific, and have large families. 
A number of papers, running to more than a hundred pages, 
attest the great interest now taken in America in the ethnology, 
antiquities, and history of the Aborigines, — if so we may call 
them. 
We come next to a memoir on the “ Present Fundamental 
Conceptions of Physics,” the substance of two lectures delivered 
in Vienna by Prof. F. J. Pisko. 
Light and Heat. The Manifestations to our Senses of the Two 
Opposite Forces of Attraction and Repulsion in Nature. 
By Capt. W. Sedgwick, R.E. London : C. F. Hodgson 
and Son. 
We can do little more at present than briefly indicate the princi- 
pal points brought forward in this pamphlet. The author con- 
siders light, the attractive force, as identical with gravity. He 
meets the objection that upon this hypothesis gravity would be 
greater by day than in the night, by arguing that “ with day- 
light comes day-heat, and heat is direCtly opposed to gravity.” 
He further suggests that if we were provided with a more deli- 
cate means of measuring the force of gravity, there would be 
found a diurnal variation in its intensity. Pleat is not identical 
with light, but its antagonist. 
The fundamental phenomenon from which he starts is the spot 
of light observed on going into a dark room, and applying pressure 
to the eye ball with the tip of the finger, preferably between the 
pupil and the nose. This spot consists of a small bright nucleus, 
surrounded by a number of rings alternately bright and dark, the 
outermost being very faint, and “ the middle ring vividly bright 
when the pressure is first applied.” If pressure is applied to the 
eye-ball in bright sunlight, the result is merely a dark spot with 
a faintly luminous border. 
A second experiment is as follows : — A piece of well-crumpled 
silver or tin-foil is laid horizontally in the full sunlight ; the eye 
is then brought to within an inch of it, but in such a manner 
that the head does not shade off the sun’s rays from the foil. 
The patches of light upon the foil revolve themselves into round 
spots, all alike in form, size, and general appearance, and each 
with five bright lines radiating from the centre. A similar spot 
with five radiating lines is seen if we look at a source of light 
