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 9
... from the landscape , which I view by look- ing through the small hole in the paper , must come in all directions at the same time . - Take another in- stance ; if a candle be placed on an eminence THE MOTION OF LIGHT . 59.
... from the landscape , which I view by look- ing through the small hole in the paper , must come in all directions at the same time . - Take another in- stance ; if a candle be placed on an eminence THE MOTION OF LIGHT . 59.
Страница 10
... stance ; if a candle be placed on an eminence in a dark night , it may be seen all round for the space of half a mile : in other words , there is no place within a sphere of a mile in diameter , where the candle cannot be seen , that is ...
... stance ; if a candle be placed on an eminence in a dark night , it may be seen all round for the space of half a mile : in other words , there is no place within a sphere of a mile in diameter , where the candle cannot be seen , that is ...
Страница 51
... ; for two concave surfaces have double the effect in refracting rays to what a single one has the latter bringing them to a focus at the distance of the diameter , the former at half that di- stance , F 2 OF THE DIFFERENT LENSES . 51.
... ; for two concave surfaces have double the effect in refracting rays to what a single one has the latter bringing them to a focus at the distance of the diameter , the former at half that di- stance , F 2 OF THE DIFFERENT LENSES . 51.
Страница 52
... stance , or of the radius . Charles . Sometimes , perhaps , the two sides of the same lens may have different curves : what is to be done then ? Tutor . If you know the radius of both the curves , the following rule will give you the ...
... stance , or of the radius . Charles . Sometimes , perhaps , the two sides of the same lens may have different curves : what is to be done then ? Tutor . If you know the radius of both the curves , the following rule will give you the ...
Страница 65
... a , and the rays from A must , for the same reason , be re- fracted to a . James . If the object A B C is brought nearer to the glass , will the picture be removed to a greater di- stance ? Tutor G 3 OF THE INVERTED IMAGE . 65.
... a , and the rays from A must , for the same reason , be re- fracted to a . James . If the object A B C is brought nearer to the glass , will the picture be removed to a greater di- stance ? Tutor G 3 OF THE INVERTED IMAGE . 65.
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...