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angle appear ascertained atmosphere attraction axis bottom called centre of gravity centrifugal force circle colours comets concave constellations convex convex lens cylinder Describe diameter direction distance diurnal motion Earth eclipse effect elastic electricity equal experiment fall feet figure fixed stars fluid focus force Give the illustration glass globe heavenly bodies heavens hence Herschel horizon inches inclined inclined plane length lens less lever liquid luminous lunar eclipse machine magnet means Mercury meridian metal miles mirror Moon motion move object oblique Observation opposite orbit parallel passing perpendicular pipes piston planet pole position pressure produced rays of light reflected reflecting telescope refraction represented retina revolution revolve rise seen side solar solar eclipse space specific gravity Sun's surface telescope tion tube valve velocity Venus vessel vibrations weight wheel wire wood-cut zinc
Page 242 - ... can be raised higher than another. The Mediterranean and Baltic seas have very small elevations, because the inlets by which they communicate with the ocean are so narrow, that they cannot, in so short a time, either receive or discharge enough, sensibly to raise or sink their surfaces.
Page 270 - ... to be the whole contents of the heavens. Allowing him now the use of a common telescope, he begins to suspect that all the milkiness of the bright path which surrounds the sphere may be owing to stars. He perceives a few clusters of them in various parts of the heavens, and finds also that there...
Page 99 - The following rules may generally be relied upon, at least to a certain extent : — 1 . Generally the rising of the mercury indicates the approach of fair weather : the falling of it shows the approach of foul weather. 2. In sultry weather the fall of the mercury indicates coming thunder. In winter the rise of the mercury indicates frost. In frost its fall indicates thaw : and its rise indicates snow.
Page 38 - These simple machines are the lever, the wheel and axle, the pulley, the inclined plane, the wedge, and the screw.
Page 118 - ... at the focus is to the common heat of the sun, as the area of the glass is to the area of the focus. Thus, if a lens, four inches in diameter, collect the sun's rays into a focus, at the distance of twelve inches, the image will not be more than one tenth of an inch in diameter ; the surface of this little circle is 1600...
Page 71 - Most very corpulent people, who are at the same time strong and healthy, would perhaps find on trial that their bodies would float on water; and those who do not happen to be endowed with a superabundance of fat might still in almost all cases, with a little application, acquire the habit of floating with facility. The capability of breathing freely and at regular intervals is essentially requisite to enable a person, to support himself on the surface of water. The head, and the upper and lower extremities...
Page 57 - E, while it both descends and ascends in F, rising equally in all the tubes, and spouting out till the water is reduced in the side tubes to the level of the summits of the internal ones, when the equilibrium being established the liquid will remain at rest. Thus it follows that any number of columns of a liquid, freely communicating, whatever may be their respective diameters and figures will always have the same vertical height.
Page 270 - Herschel says, that in the most crowded part of the milky way he has had fields of view that contained no less than 588 stars, and these were continued for many minutes, so that, in a quarter of an hour, he has seen 116,000 stars pass through the field view of a telescope of only 15' aperture : and at another time, in 41 minutes, he saw 258,000 stars pass through the field of his telescope.