Post by Admin on Oct 9, 2016 10:33:15 GMT
CHAP. XXVI.
Of Prospective, and Looking-Glasses.
TO return to Opticks, to which the use of Look∣ing-Glasses and Prospective-Glasses does mainly conduce; the Experiments whereof are daily seen in the various kinds of Glasses, Hollow, Convex, Plane, Pil∣lar-fashion'd, Pyramidal, Globular, Gibbose, Orbicular, full of Angles, Inverted, Everted, Regular, Irregular, Solid and Perspicuous. So we read, as Celius in his ancient Readings relates, That one Hostius, a Person of an Obscene Life, made a sort of Glasses that made the Object seem far greater than it was; so that one Finger should seem to exceed the whole Arm, both in bigness and thickness. There is also a sort of Glass, wherein a man may see the Image of another man, but not his own; and another, which being set in such a posture and place, gives back no representation; but the posture being alter'd, presently returns the Ob∣ject presented. Some that shew all sorts of Represen∣tations; some not all, but many. Other Glasses there are, that contrary to the fashion of all others, will shew the right hand directly opposite to the Right, and the Left directly opposite to the Left. Other Glasses there are that do not represent the Image with∣in, but as it were hanging in the Air. Burning-Glasses there are too, that Collecting the beams of the Sun into one point, kindle fire at a distance upon any Combusti∣ble Matter. Little Perspicuous Glasses also are not without thier Impostures; that is to say, to make a lit∣tle thing appear great; those that are afar off, neer; those things or places that are neer, afar off; those that are above us, below us; those things that are below us,
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above us, or in any other posture or situation whatever. There are other of these Glasses that make one Object appear to be many, and will represent things with di∣vers Colours like the Rainbow; as also, in divers Shapes and Figures. And I my self have learnt to make Glasses, wherein, while the Sun shines, you may discern for the distance of Three or Four Miles toge∣ther, whatever places are enlightned or over-spread with his Beams. And this is to be admired in plain Glasses, that by how much the less they are, so much less than themselves they will represent the Object; but let them be never so big, yet shall they not repre∣sent the Object ever a whit the larger: which when St. Austin consider'd, writing to Nibridius, he conceives it to be something of an occult Mystery. However, they are vain and useless things, invented only for Ostentation and idle Pleasure. Many both Greek and Latine have Treated of Looking-Glasses and Perspectives, but above all the rest, Vitellius.
Of Prospective, and Looking-Glasses.
TO return to Opticks, to which the use of Look∣ing-Glasses and Prospective-Glasses does mainly conduce; the Experiments whereof are daily seen in the various kinds of Glasses, Hollow, Convex, Plane, Pil∣lar-fashion'd, Pyramidal, Globular, Gibbose, Orbicular, full of Angles, Inverted, Everted, Regular, Irregular, Solid and Perspicuous. So we read, as Celius in his ancient Readings relates, That one Hostius, a Person of an Obscene Life, made a sort of Glasses that made the Object seem far greater than it was; so that one Finger should seem to exceed the whole Arm, both in bigness and thickness. There is also a sort of Glass, wherein a man may see the Image of another man, but not his own; and another, which being set in such a posture and place, gives back no representation; but the posture being alter'd, presently returns the Ob∣ject presented. Some that shew all sorts of Represen∣tations; some not all, but many. Other Glasses there are, that contrary to the fashion of all others, will shew the right hand directly opposite to the Right, and the Left directly opposite to the Left. Other Glasses there are that do not represent the Image with∣in, but as it were hanging in the Air. Burning-Glasses there are too, that Collecting the beams of the Sun into one point, kindle fire at a distance upon any Combusti∣ble Matter. Little Perspicuous Glasses also are not without thier Impostures; that is to say, to make a lit∣tle thing appear great; those that are afar off, neer; those things or places that are neer, afar off; those that are above us, below us; those things that are below us,
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above us, or in any other posture or situation whatever. There are other of these Glasses that make one Object appear to be many, and will represent things with di∣vers Colours like the Rainbow; as also, in divers Shapes and Figures. And I my self have learnt to make Glasses, wherein, while the Sun shines, you may discern for the distance of Three or Four Miles toge∣ther, whatever places are enlightned or over-spread with his Beams. And this is to be admired in plain Glasses, that by how much the less they are, so much less than themselves they will represent the Object; but let them be never so big, yet shall they not repre∣sent the Object ever a whit the larger: which when St. Austin consider'd, writing to Nibridius, he conceives it to be something of an occult Mystery. However, they are vain and useless things, invented only for Ostentation and idle Pleasure. Many both Greek and Latine have Treated of Looking-Glasses and Perspectives, but above all the rest, Vitellius.