Scientific Dialogues: Intended for the Instruction and Entertainment of Young People, Inwich the First Principles of Natural and Experimental Philosophy are Fully Explained. Vol. II, IV-VI.J. Johnson, 1809 |
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Страница 38
... feet deep , which is sufficient to drown you or me , if we cannot swim : I say the bottom will appear to be only four feet and a half from the surface , in which case you could . stand and have the greater part of your head above it ...
... feet deep , which is sufficient to drown you or me , if we cannot swim : I say the bottom will appear to be only four feet and a half from the surface , in which case you could . stand and have the greater part of your head above it ...
Страница 54
... feet in diameter , and when fixed in its frame , it exposes a clear surface of more than two feet eight inches in diameter , and its focus , by means of another lens , was reduced to a dia- meter of half an inch . The heat produced by ...
... feet in diameter , and when fixed in its frame , it exposes a clear surface of more than two feet eight inches in diameter , and its focus , by means of another lens , was reduced to a dia- meter of half an inch . The heat produced by ...
Страница 105
... ? Tutor . Yes : but we have no cer- tain accounts that may be implicitly relied on . M. Buffon , about fifty or sixty years ago , burned a plank at the distance of seventy feet , with forty plain mirrors OF PLAIN MIRRORS . 105.
... ? Tutor . Yes : but we have no cer- tain accounts that may be implicitly relied on . M. Buffon , about fifty or sixty years ago , burned a plank at the distance of seventy feet , with forty plain mirrors OF PLAIN MIRRORS . 105.
Страница 106
... feet , with forty plain mirrors . James . I do not see how they can act as burning glasses . Tutor . A plain mirror reflects the light and heat coming from the sun , and will illuminate and heat any sub- stance on which they are thrown ...
... feet , with forty plain mirrors . James . I do not see how they can act as burning glasses . Tutor . A plain mirror reflects the light and heat coming from the sun , and will illuminate and heat any sub- stance on which they are thrown ...
Страница 130
... feet long , and fifteen inches wide , is to be placed a concave mirror ; near the upper part of the opposite end a hole is made , and about the middle of the box is placed a hollow frame of pasteboard that confines the view of the ...
... feet long , and fifteen inches wide , is to be placed a concave mirror ; near the upper part of the opposite end a hole is made , and about the middle of the box is placed a hollow frame of pasteboard that confines the view of the ...
Често срещани думи и фрази
A B C A B Plate angle of incidence angle of reflection appear attract body called Charles colours compass concave lens concave mirror CONVERSATION convex lens convex mirror dark diameter direction distinct vision diverge double convex equal eye-glass farther feet figure flected focal distance focus of parallel formed half humours inches incident rays inverted image iron James ject lenses Let A B light flowing look looking-glass magnifying power means microscope move nearer needle nosegay object object-glass optic optic nerve painted parallel rays pass pencil of rays perpendicular piece plain mirror Plate 11 proceed radius rainbow rays fall rays flowing rays of light reflected rays reflecting telescope refraction retina seen shutter side small hole south pole spectator stance stand steel Suppose surface throw tion transparent tube Tutor violet vitreous humour
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Страница 80 - Seasons return, but not to me returns Day, or the sweet approach of ev'n or morn, Or sight of vernal bloom, or summer's rose, Or flocks or herds or human face divine ; But cloud instead, and ever-during dark Surrounds me, from the cheerful ways of men Cut off, and for the book of knowledge fair Presented with an universal blank Of nature's works, to me expung'd and ras'd, And wisdom at one entrance quite shut out.
Страница 85 - First the flaming red Sprung vivid forth ; the tawny orange next ; And next delicious yellow ; by whose side Fell the kind beams of all-refreshing green. Then the pure blue, that swells autumnal skies, Ethereal...
Страница 8 - How distant some of these nocturnal suns ! So distant (says the sage) 'twere not absurd To doubt, if beams, set out at nature's birth, Are yet arriv'd at this so foreign world ; Though nothing half so rapid as their flight.
Страница 109 - ... as the angle of reflection is always equal to the angle of incidence, the image for any point can be seen only in the reflected ray prolonged.
Страница 166 - Meantime, refracted from yon eastern cloud, Bestriding earth, the grand ethereal bow Shoots up immense; and every hue unfolds, In fair proportion, running from the red To where the violet fades into the sky.
Страница 172 - Died in the fainting Violet away. These, when the clouds distil the rosy shower, Shine out distinct adown the watery bow ; While o'er our heads the dewy vision bends Delightful, melting on the fields beneath. Myriads of mingling dyes from these result, And myriads still remain ; infinite source Of beauty, ever blushing, ever new. Did ever poet image aught so fair, Dreaming in whispering groves, by the hoarse brook; Or prophet, to whose rapture heaven descends...
Страница 187 - Yes; the three glasses next the eye baving their focal distances equal, the magnifying power is found by dividing the focal distance of the object-glass by the focal distance of one of. the eye-glasses.
Страница 49 - A lens is glass ground into such a form, as to collect or disperse the rays of light which pass through it. These are of different shapes, and from thence receive different names.
Страница 61 - If anoto glass, FG, of the same convexity as DE, be placed in the rays at the same distance from the focus, it will refract them so, as that, after going out of it, they will be all parallel...