Page:The wonders of optics (1869).djvu/229

 head in fig. 63, and that the lower you place the candle the greater will be the deformity. You may if you please, trace the luminous figure on the paper, and the result will appear distorted when looked at in the ordinary manner, but symmetrical when viewed from the point at which the flame of the candle was placed.

In the foregoing experiments we have spoken of the anamorphic drawings as being placed in a horizontal position, but they may be looked at just as well vertically, the card with the hole being in this instance horizontal. It is also not necessary that the point of sight (, fig. 63) should be in the centre of the picture; it may be placed at one side or the other, care being taken to draw all the divisional lines so that they meet at this particular spot. A few experiments with a candle and a perforated figure will soon show the student how to accomplish this.

Anamorphoses by reflection may be prepared, if this principle is carried out, which appear a mass of confused lines until they are reflected in a cylindrical mirror. Formerly opticians were accustomed to construct anamorphoses which became symmetrical pictures when viewed in a conical mirror; but the fashion for such toys appears to have gone out. Such drawings were extremely difficult to make, and the mirrors, having to be ground and polished with great care, were very expensive.

Some experimentalists have carried the subject so far that, by looking at the drawing of an object in particular positions, it changed into quite a different subject. In the cloister of an abbey that once existed in Paris, there were two anamorphoses of this kind. They were the work of a certain Father Niceron, who has left behind him a treatise in Latin on optical wonders, entitled Thaumaturgus Opticus, which contains a long essay on anamorphoses. One of these pictures repre