In the side of the lantern an aperture is cut, and around it is fixed a small triangular box containing a mirror set at an angle of forty-five degrees, and having a lens, in the base, of a very low power, or hardly any power at all. At the top of this side-box is fixed an adjustable lens of the same type as that in front of the lantern. In the lantern itself is placed a slide representing a landscape, an interior, etc., and the image of this is thrown on to the screen. At the back of the side-box is placed a praxinoscope of novel construction, and the images from it are thrown on to the sheet through the lens at its top, so that, as in a dissolving view, we have the picture seen by the assembly built up out of the slides.
The praxinoscope consists of a crown of mirrors sloping inwards, surrounded by a ring constructed to take a set of glass slides mounted in a strip by means of connecting links of silk or calico. The slides consist each of one of the figures alluded to in the last section, which form the series of instantaneous photographs that have revolutionised our ideas of the details of motion. They are, in fact, zoetropic pictures, each differing but slightly in attitude from the other, and each representing one of the changes assumed in a complete round of some definite movement.
The slides are slipped into the ring. The light from the lantern shining through the glass throws the images on to the praxinoscopic mirror, and thence it is reflected through the top lens on to the screen. The ring and crown are arranged at the angles given in the cut, and when the slides are revolved by means of the band and pulley shown below them, the different pictures as they pass the lens are reflected on to the background, and the figure appears in lifelike movement.
The lantern praxinoscope thus makes the zoetropic effects visible to a large assembly seated at their ease, and gives pictures of heroic size instead of the tiny proportions with which, when confined to the ordinary instrument, we are forced to be content. Many modifications of the arrangement will readily suggest themselves to our readers, and need not therefore be specially described.
Some Typical Boats.