Conversations on Natural Philosophy |
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angle aperture appear atmosphere attraction axis ball called camera obscura Caroline centre of gravity centrifugal force centripetal force circle cohesion coloured rays concave mirror consequently convex degrees dimensions diminished direction distance diurnal motion draw earth eclipse effect elastic Emily equal equator explain fall obliquely fixed stars fluids focus force of projection fulcrum glass globe greater heat idea lens less lever lighter luminous magnified mercury meridian moon motion move natural philosophy nature object observe opposite orbit particles passes perfectly perpendicular planets plate polar circles pole pressure proceed produce pulley pump pupil rays fall rays of light reflected rays refracting telescope refraction represent resistance retina revolve right line rise round the sun shadow shine situated solid bodies sonorous body space specific gravity spring sun's rays suppose surface tion tube understand vapour velocity vibrations weight whilst wind YORK PUBLIC LIBRARY
Popular passages
Page 75 - 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 76 - The starry host, rode brightest, till the moon, Rising in clouded majesty, at length, Apparent queen, unveil'd her peerless light, And o'er the dark her silver mantle threw.
Page 86 - 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 55 - ... 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 32 - A, a little on one side, — now let it go ; — it strikes, you see, against the other ball, B, and drives it off, to a distance equal to that through which the first ball fell ; but the motion of A is stopped, because, when it struck B, it received in return a blow equal to that which it gave, and its motion was consequently destroyed.
Page 189 - We cannot, however, see an object distinctly, if we bring it very near to the eye, because the rays fall on the crystalline humour too divergent to be refracted to a focus on the retina. The confusion, therefore, arising from viewing an object too near the eye, is similar to that which proceeds from a flattened crystalline humour ; the rays reach the retina before they are collected to a focus (.fig.
Page 189 - 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 180 - The white rays of the sun are composed of coloured rays, which, when blended together, appear colourless or white. Sir Isaac Newton, to whom we are indebted for the most important discoveries respecting light and colours, was the first who divided a white ray of light, and found it to consist of an assemblage of coloured rays, which formed an image upon the wall, such as you now see exhibited (fig.
Page 15 - ... are so strongly attracted by the earth, as to resist every other impulse; otherwise they would necessarily move towards the hills and the mountains; but the lesser force must yield to the greater. There are, however, some, circumstances in which the attraction of a large body has sensibly counteracted that of the earth. If...
Page 92 - We shall now explain the variation of the seasons, and the difference of the length of the days and nights in those seasons — both effects resulting from the same cause.