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 13
... world was round like a ball , instead of being flat as she had supposed , and that it was surrounded by the air she asked me what supported it . I told her that This it required no support ; she then enquired why it 2.
... world was round like a ball , instead of being flat as she had supposed , and that it was surrounded by the air she asked me what supported it . I told her that This it required no support ; she then enquired why it 2.
Page 21
... ball I am obliged to use all my strength to give a rapid motion to the ball ; and when I have to catch it , I am sure I feel the resistance it makes to being stopped . But if I did not catch it , it would soon fall to the ground and ...
... ball I am obliged to use all my strength to give a rapid motion to the ball ; and when I have to catch it , I am sure I feel the resistance it makes to being stopped . But if I did not catch it , it would soon fall to the ground and ...
Page 22
... ball ceases to move , therefore , it must be stopped by some other cause or power ; but as it is one with which you are yet unacquainted , we cannot at present inves- tigate its effects . The last property which appears to be common to ...
... ball ceases to move , therefore , it must be stopped by some other cause or power ; but as it is one with which you are yet unacquainted , we cannot at present inves- tigate its effects . The last property which appears to be common to ...
Page 41
... ball , than it does to support the weight of a ball ( of the same size ) made of leather ; but the cannon - ball will overcome this resistance more easily , and fall to the ground , consequently , quicker than the leather ball ...
... ball , than it does to support the weight of a ball ( of the same size ) made of leather ; but the cannon - ball will overcome this resistance more easily , and fall to the ground , consequently , quicker than the leather ball ...
Page 42
... ball : it offers now but a small surface to the air , and encounters therefore but little resistance : see how much more rapidly it falls . The heaviest bodies may be made to float awhile in the air , by making the extent of their ...
... ball : it offers now but a small surface to the air , and encounters therefore but little resistance : see how much more rapidly it falls . The heaviest bodies may be made to float awhile in the air , by making the extent of their ...
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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?...