e, depend upon the combined action of heaven and
earth."--HUMBOLDT.

_The Sun's Body Dark._

5. (Page 30.) "HERSCHEL'S fixed idea was that the darkness of a spot was
an indication of a cool habitable globe."

_A New Theory of the Nature of Water._

6. (Page 36.) M. MAICHE, in _Les Mondes_, propounds the theory, reached
after numerous experiments, that water is simply hydrogen _plus_
electricity, or oxygen _minus_ electricity, or, in other words, that
normal electrified hydrogen constitutes water, and that normal
diselectrified oxygen produces the same; or that hydrogen, oxygen, and
water are precisely the same, differing only in degree of
electrification.

_Sun-heat._

7. (Page 41.) "The sun, as the main source of heat and light, must be
able to call forth and animate magnetic forces on our planet."--HUMBOLDT.

"It is an incontestable fact that the sun exercises an action upon the
magnetic phenomena which are manifested upon our globe."--SECCHI.

"What is certain is, that there ought to be, between the sun and
planets, a means of communication of force, and the transmission of
movement."--_Ibid._

"The central body may, as a powerful source of heat, excite magnetic
activity on our planet."--HUMBOLDT.

8. (Page 42.) "It cannot be doubted that electro-magnetic currents exist
in the interior of the globe."--AMPERE.

"The internal heat of our planet is connected with the generation of
electro-magnetic currents."--HUMBOLDT.

"A large proportion of winter heat of the poles comes through the
equatorial current."--YOUMANS.

_Aurorae._

9. (Page 44.) "HOOD heard a noise as of quickly moved musket-balls, and
a slight crackling sound during an aurora. He also noticed the same
noise on the following day."

"FATHER PERRY of the Stonyhurst Observatory remarked that the green
spectroscopic line characteristic of the aurora, could be detected even
where the unassisted eye failed to notice any trace of light."

"The fleecy clouds seen in Iceland by THIENEMANN, and which he
considered to be the northern light, have been seen in recent times by
FRANKLIN and RICHARDSON, near the American north pole, and by ADMIRAL
WRANGEL on the Siberian coast. All remarked that the aurora flashed
forth in the most vivid beams when masses of cirrus strata were hovering
in the upper regions of the air, and when these were so thin th