A Grammar of Natural and Experimental Philosophy ...: With One Hundred Engravings on Wood |
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angle aphelion apparent magnitude appear apsis atmosphere attraction axis called centre of gravity centrifugal force centripetal forces circle colours concave conductor converging convex convex lens degrees described diameter direction diurnal motion diverge earth earth's orbit ecliptic elastic electrified equal Excentricity in miles eye-glass fall fixed stars focal distance focus galvanic glass greater heat Hence Herschel horizon Illus inches inferior conjunction Jupiter latitude lens less lever longitude magnet mean distance mercury meridian metal moon moon's move nearer node object object-glass observation opposite orbit parallax particles pass pendulum perihelion perpendicular piece piston planet plate poles precession pressure produced projectile force proportion quantity rays of light reflected refraction retina revolves rise round Saturn Secular motion seen semi-diameter side Sidereal revolution space specific gravity substances sun's surface syzygies telescope tion tube velocity Venus vessel vibrations weight whence
Popular passages
Page 107 - On the tops of mountains of sufficient height, at the altitude where clouds can seldom reach to shelter them from the direct rays of the sun, we always find regions of ice and snow. Now, if the solar rays themselves conveyed all the heat we find on this globe, it ought to be hottest where their course is the least interrupted. Again, our aeronauts all confirm the coldness of the upper regions of the atmosphere...
Page 67 - All the parallel rays of the sun which pass through the glass, are collected together in the focus; and, consequently, the heat 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 times less than the surface of the lens, and, consequently,...
Page 167 - When pieces of charcoal about an inch long and onesixth of an inch in diameter, were brought near each other (within the thirtieth or fortieth part of an inch) a bright spark was produced, and more than half the volume of 'the charcoal became ignited to whiteness, and by withdrawing the points from each other a constant discharge took place through the heated air, in a...
Page 131 - If the orbit of the earth and that of the moon were both in the same plane, there would be an eclipse of the sun at every new moon, and an eclipse of the moon at every full moon.
Page 106 - Hence he concludes, that the sun has a very extensive atmosphere, which consists of elastic fluids that are more or less lucid and transparent ; and of which the lucid ones furnish us with light. This atmosphere, he...
Page 48 - If a thin glass vessel, whose aperture is closed, be placed under the receiver of an air-pump, and the air exhausted from the receiver, the vessel will be broken by the pressure of air within.
Page 98 - The Azimuth of a heavenly body, is the arc of the horizon intercepted between...
Page 40 - Steam is thus supplied' from a large boiler, which, in forcing up the piston, instantly opens a valve, through which cold water rushes, on the principle of the common pump. Other steam is then introduced above the piston, which forces it down again, and drives the water out of the pipe with immense force.
Page 167 - It consists of two hundred instruments, connected together in regular order, each composed of ten double plates arranged in cells of porcelain, and containing in each plate thirtytwo square inches ; so that the whole number of double plates is 2000, and the whole surface 128,000 square inches.