Fronts of the four lanterns, showing how the dissolving mechanism is arranged.
"Behind the scenes" always has a great attraction for young people; we have, therefore, in the frontispiece, with the help of Mr. Hine (who painted a great number of the photographs shown at the Polytechnic during the author's management), given a section of the large theatre taken whilst the effective scene of the Siege of Delhi was in progress. The optical effects were assisted by various sounds in imitation of war's alarms, for the production of which, more volunteers than were required would occasionally trespass behind the screen, and produce those terrific sounds that some persons of a nervous temperament said were really stunning. In a page picture, we have also given a correct drawing of the interior of the optical box at the Polytechnic, with the four fixed lanterns, and side cupboards to hold the glass pictures. The four lanterns worked on a railway, with wheels and a circular turn-table; they could be removed, and the microscope arranged in their places.
Before and behind the screen at the Polytechnic during the exhibition of the dioramic effects of the siege of Delhi.
III. The Oxy-Hydrogen Microscope.
Many persons will recollect the first exhibition of this instrument in Bond-street, by Mr. J. T. Cooper, and Mr. Cary, succeeded by the Adelaide Gallery exhibition of scientific wonders and an oxy-hydrogen microscope. The apparatus for this purpose consists of three condensing lenses and an object glass. The objects, such as live aquatic insects, are placed in glass troughs containing water; the other objects, ferns, feathers, butterflies, algæ, &c. &c., being mounted on slides in the ordinary way with Canada balsam. (Fig. 298.)
Fig. 298.
a. The lime light. c c c. Condensers. d. The object, such as a tank of water containing live insects. e. The object glasses.