In the first figure df are glasses so disposed asto be turned at pleasure into their proper placeat the joint c. The second figure shows theinstrument on its stand, and clamped to abook. The joint by which the prism isattached to the stand is double. Camera Obscura (in painting), an opticalmachine,… … effects of the weather. Its construction maybe explained as follows :—In the extremity ofthe arm, p q, that extends from the side of asmall square box, b l, is placed a double con-vex lens, whose axis is inclined in an angle offorty-five degrees, to a plane mirror, b o ; thefocal length of the lens…
Design · Decoration and ornament · Art
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