Conversations on Natural Philosophy: In which the Elements of that Science are Familiarly Explained and Adapted to the Comprehension of Young Pupils : Illustrated with PlatesJ.Y. Humphreys, 1821 - 311 pages |
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Page 146
... vibrate . Without being put in motion , a pen- dulum , like a plumb line , hangs perpendicular to the general surface of the earth , by which it is attracted ; but , if you raise a pendulum , gravity will bring it back to its ...
... vibrate . Without being put in motion , a pen- dulum , like a plumb line , hangs perpendicular to the general surface of the earth , by which it is attracted ; but , if you raise a pendulum , gravity will bring it back to its ...
Page 147
... vibrations per- fectly regular : being of equal distances , and performed in equal times . Emily . That is the natural result of the uniformity of the power which produces these vibrations , for the force of gravity being always the ...
... vibrations per- fectly regular : being of equal distances , and performed in equal times . Emily . That is the natural result of the uniformity of the power which produces these vibrations , for the force of gravity being always the ...
Page 148
... vibrations of a pendulum depends on its length ; and when it is said , that a pendulum vibrates quicker at the pole than at the equator , it is supposing it to be of the same length . A pendulum which vibrates a second in this latitude ...
... vibrations of a pendulum depends on its length ; and when it is said , that a pendulum vibrates quicker at the pole than at the equator , it is supposing it to be of the same length . A pendulum which vibrates a second in this latitude ...
Page 228
... vibration , at the end of which it will retain sufficient velocity to bring it to E , and back again to F which constitutes its second vibration ; the third vibration will carry it only to G and H , and so on till the resistance of the ...
... vibration , at the end of which it will retain sufficient velocity to bring it to E , and back again to F which constitutes its second vibration ; the third vibration will carry it only to G and H , and so on till the resistance of the ...
Page 229
... vibrations , and are composed of a motion forwards and backwards , similar to those of the sonorous body . They differ also in the one taking place in a plane , the other in all directions . The aerial undulations being spherical ...
... vibrations , and are composed of a motion forwards and backwards , similar to those of the sonorous body . They differ also in the one taking place in a plane , the other in all directions . The aerial undulations being spherical ...
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Common terms and phrases
angle appear atmosphere attraction axis ball called camera obscura Caroline centre of gravity centrifugal force circle cohesion colored rays concave mirror consequently convex cricket ball dark degrees descend dimensions diminishes direction distance diurnal motion draw earth eclipse effect elastic Emily equal equator equilibrium fixed stars fluids focus fulcrum glass globe greater heat heavier inclined plane lens less lever lighter luminous body mechanical power mercury meridian moon move nature object observe opaque body opposite orbit particles passes perfectly perpendicularly planets plate pole Pray pressure proceed produced proportion pulley pump quantity rays fall rays of light re-action recollect reflected rays refraction represents reservoir resistance retina revolution revolve round rise round the sun screw shadow shine situated solid bodies sonorous body space specific gravity sphere string sun's rays supported suppose surface tides tion tube understand velocity vibrations weight wheel whilst wind
Popular passages
Page 126 - ... things clad; Silence accompanied; for beast and bird, They to their grassy couch, these to their nests Were slunk, all but .the wakeful nightingale; She all night long her amorous descant sung; Silence was pleased: now...
Page 140 - evidence of things not seen," in the fulness of Divine grace ; and was profound on this, the greatest concern of human life, while unable even to comprehend how the " inclination of the earth's axis to the plane of its orbit" could be the cause of the change of the seasons.
Page 125 - Now came still evening on, and twilight gray Had in her sober livery all things clad ; Silence accompanied ; for beast and bird, They to their grassy couch, these to their nests Were slunk, all but the wakeful nightingale ; She all night long her amorous descant sung...
Page 98 - ... time that the axle describes a small one, therefore the power is increased in the same proportion as the circumference of the wheel is greater than that of the axle. If the...
Page 291 - The construction of the eye is so admirable, that it is capable of adapting itself, more or less, to the circumstances in which it is placed. In a faint light the pupil dilates so as to receive an additional quantity of rays, and in a strong light it contracts, in order to prevent the intensity of the light from injuring the optic nerve.
Page 103 - When, therefore, the surfaces of the two bodies come into contact, the prominent parts of the one will often fall into the hollow parts of the other, and occasion more or less resistance to motion. In proportion as the surfaces of bodies are well polished, the friction is diminished; but it is always considerable, and it is usually computed to destroy one-third of the power of a machine.
Page 43 - ... regions. The pressure of the atmosphere has been compared to that of a pile of fleeces of wool, in which the lower fleeces are pressed together by the weight of those above : these lie light and loose, in proportion as they approach the uppermost fleece, which receives no external pressure, and is confined merely by the force of its own gravity.
Page 76 - The curve-line which the ball has described, is called in geometry, a parabola; but when the ball is thrown perpendicularly upwards, it will descend perpendicularly ; because the force of projection, and that of gravity, are in the same line of direction. We have noticed the centres of magnitude, and of motion ; but I have not yet explained to you what is meant by the centre of gravity ; it is that point in a body, about which all the parts exactly balance each other ; if, therefore, that point is...
Page 294 - By the assistance of such glasses, therefore, the rays from a distant object fall on the pupil as divergent as those from a less distant object ; and, with short-sighted people, they throw the image of a distant object back as far as the retina.
Page 301 - XY (fig. 2.) in it, to converge the rays to a focus on the object A B. There is but one thing more wanting to complete .the solar microscope, which I shall leave to Caroline's sagacity to discover. CAROLINE. Our microscope has a small mirror attached to it, upon a moveable joint, which can be so adjusted as to receive the sun's rays, and reflect them upon the object. If a similar mirror were placed to reflect light upon the lens, would it not be a means of illuminating the object more perfectly?...