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whether those who have contributed most effectually to the advancement of the sciences, have rigidly adhered to Bacon's rules. And, in general, such a rigid adherence is unnecessary; because so much assistance can, in general, be derived from what knowledge has been already acquired, that a rigid natural historical detail of all the phenomena becomes unnecessary. It was only in the infancy of science that such details were requisite. Boyle often draws them up in his inquiries into the cause of various phenomena, and his investigations were of considerable use in forwarding those branches of science which he cultivated. Bacon also was mistaken in conceiving that, by investigation, mankind may become acquainted with the essences of the powers and qualities residing in bodies. So far as science has hitherto advanced, no one essence has been discovered, either as to matter or as to any of its more extensive modifications. Thus we are still in doubt whether heat and electricity be qualities or substances. Yet we have discovered many important properties or laws, by means of which heat and electricity, whether properties or substances, are regulated. And from this knowledge, probably, we derive as much advantage as could be obtained from a complete knowledge of their essence.

By experiment or observation all the new facts in every science are acquired. By the application of mathematical reasoning to these facts, they are reduced to the requisite simplicity, and the general principles which regulate every particular science determined.



[NOTE.-The volumes are indicated by the numeral letters i., ii., and the page by the figures.]


Action and reaction, ii. 197–204.
Æpinus, his works, i. 133.

Air, elasticity of, ii. 41-60; substance and
color of, i. 193; weight of, i. 194; inertia
of, i. 195; impenetrability of, i. 196; ii. 31.
Air, elasticity and compressibility of, i. 198;
ii. 31.

Air-drawn dagger, illusion of, i. 264.
Air-pump, the, ii. 47-56, 423.
Alcohol thermometer, ii. 138.
Aldebaran, ii. 338.

Ampère on electro-magnetism, ii. 122; his
theory of terrestrial magnetism, ii. 125.
Analysis of the heavens, ii. 378.
Anecdote of Napoleon, i. 369.

Animal and vegetable life sustained by the
atmosphere, i. 59.

Ancient method of directing lightning, ii. 99.
Animalcules, their minute organization, &c.,
ii. 25.

Animal electricity, i. 364.

Annual motion of the earth, i. 480.
Annual variation of the electricity of the
air, ii. 154.

Apparatus for observing the electricity of
the atmosphere, ii. 149, 150.
Appearance accompanying meteors, i. 460.
Arago shows how comets may be made to as-
sume different degrees of brightness, i. 517.
Arago's observations on silent lightning, i.
552; his calculation of the quantity of
lightning drawn down by a conductor, ii.
Arcturus, ii. 339.

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Artificial freezing, Leslie's method of, ii. 171.
Artificial light, heat of, ii. 193.
Artificial magnets, construction of, ii. 113.
Astronomical and arithmetical calculations,
i. 183.

Atlantic steamers, retrospect of, i. 269.
Atlantic steam question, the project dis-
cussed and reviewed, i. 337-358.
Atlantic storms, the overwhelming force of,
urged as an objection to Atlantic steam
voyaging, i. 355.

Atmosphere, the, i. 58-64, 193-202; limited

height of, i. 198; ordinary state of, ii. 151.
Atmosphere of the planets, i. 60; of Saturn,
i. 246; of Ceres and Pallas, i. 207.
Atmosphere, various states of (vide Atmo-
spheric Electricity), ii. 149.
Atmospheric air, i. 193-202.

Atmospheric currents at Jupiter, i. 241.
Atmospheric electricity, i. 137; ii. 149-160.
Atmospheric engine invented by Newcomen,
ii. 411.

Atmospheric pressure, i. 295, 296; probably
first discovered from the effects of suction
by the mouth, i. 285; the pump cannot
act in the absence of atmospheric pres-
sure, 11, 53; effects of atmospheric pres-
sure at boiling point, ii. 303; upon the
boiling of water, ii. 305.
Atmospheric tides, i. 409.
Atoms, or molecules, ii. 22.
Atoms, ultimate, ii. 26.

Attraction and repulsion of electric cur-
rents, law of, ii. 120.

Aurora Borealis, the, i. 89-100; the effect
of atmospheric electricity, i. 137.

Arms and feet, motions and positions of, ii. Aurora, phenomenon of, noticed by the

Arms of the lever, ii. 247.

ancients, i. 100.

Auroral character of falling stars, i. 98.

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