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acid action Ampere aperture appear ascer attraction axis ball battery body centre centre of gravity circle colours compass concave conductor convex convex lens copper cylinder degree diameter direction distance earth effect elec electric current electric fluid electroscope equal experiments Fahrenheit focus force galvanic glass gravity heat horizontal hygrometer inch induction instrument intensity iron length lens lenses lever light magnet ment mercury meridian metal microscope motion move needle Newton north pole object object-glass obliquely observed opposite parallel particles passing perpendicular phenomena piece placed plane plate polarity portion position prism produced proportion pyrometer quantity rays rection reflected refraction rendered repulsion retina right angles ring round side south pole spherical aberration steel substance surface telescope temperature terrestrial magnetism theory thermometer thickness tion tricity tube velocity vertical voltaic weight wire zinc
Page 62 - And these things being rightly dispatched, does it not appear frOm phenomena, that there is a Being incorporeal, living, intelligent, omnipresent, who in infinite space, as it were, in his sensory, sees the things themselves intimately, and thoroughly perceives them, and comprehends them wholly by their immediate presence to himself...
Page 44 - ... that the vibrations thus excited are propagated in the refracting or reflecting medium or substance, much after the manner that vibrations are propagated in the air for causing sound and move faster than the rays so as to overtake them...
Page lxvii - Besides, in such situations, you are more exposed both to heat and cold ; for though the atmosphere is itself transparent, its lower regions abound with vapours and exhalations from the earth, which float in it, and act in some degree as a covering, which preserves us equally from the intensity of the sun's rays, and from the severity of the cold.
Page 44 - Those that are averse from assenting to any new discoveries, but such as they can explain by an hypothesis, may for the present suppose, that as stones by falling upon water put the water into an undulating motion, and all bodies by percussion excite vibrations in the air; so the rays of light, by impinging on any refracting or reflecting surface, excite vibrations in the refracting or reflecting medium or substance...
Page 43 - Every ray of light in its passage through any refracting surface, is put into a certain transient constitution or state; which, in the progress of the ray, returns at equal intervals, and disposes the ray at every return to be easily transmitted through the next refracting surface ; and between the returns to be easily reflected by it.
Page 6 - If the uniting wire be placed in a horizontal plane under the magnetic needle, all the effects are the same as when it is above the needle, only they are in an opposite direction; for the pole of the magnetic needle next the negative end of the battery declines to the east.
Page 81 - From the preceding facts we may likewise collect that this conflict performs circles; for without this condition, it seems impossible that the one part of the uniting wire, when placed below the magnetic pole, should drive it towards the east, and when placed above it towards the west; for it is the nature of a circle that the motions in opposite parts should have an opposite direction.
Page xxvi - The velocity of the circumference of the wheel is as much greater than that of the axle, as it is further from the centre of motion : for the wheel describes a...
Page xviii - ... 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.