The method of employing this arrangement of lenses for microscopic purposes is as follows:—Having darkened the room, and by means of the mirror reflected the sun’s rays on the glasses in a direction parallel to the axis, place some small object between the two moveable plates of glass, or affix it to one of them with very transparent gum-water, and bring it exactly into the axis of the tube; if the moveable tube be then pushed out or drawn in, till the object be a little beyond the focus, it will be seen painted very distinctly on a card, or piece of white paper, held at a proper distance, and will appear to be greatly magnified. A small insect will appear as a large animal, a hair as big as a walking-stick, and the almost invisible eels in paste or vinegar as large as common eels.
ANAMORPHOSES.
This is a very curious optical effect, producing a distorted and grotesque figure from a regular one. The term is derived from two Greek words, signifying a distortion of figure, and by its means many optical puzzles may be produced geometrically.
Take any subject, such as the portrait of a head; divide it vertically and horizontally with parallel lines, of which the outer sides shall form the boundary, A, B, C, D, and the whole shall be equidistant. Then, on a separate piece of paper, or cardboard, prepare a drawing similar to [Fig. 2] by the following means:—
1. Draw a horizontal line, a b, equal to A B, and divide it into as many equal parts as the latter is divided.
2. Let fall a perpendicular line, e v, from the middle of a b, and then draw s v parallel to a b.
3. Both e v and s v may be any length at pleasure, but the longer the first is, and the shorter the other, so will the anamorphoses be more and more deformed. The proportions in our figures are sufficiently different.
4. After having drawn from the point v right lines, v 1, v 2, v 3, v 4, to the divisions of a b, draw the line s b, and through each point where s b intersects the divergent lines draw other horizontal lines parallel to a b. We now have a trapezium, a b c d divided into as many cells as the square in [Fig. 1].
