232 ANNUAL OF SCIENTIFIC DISCOVERY. 



graphic or other prints to form one picture. The pictures must be fac- 

 similes or duplicate impressions, on semi-transparent material. If the in- 

 vention is to be applied to photographs, let two copies be taken in the usual 

 way, upon photographic paper. The paper of the two pictures is then ren- 

 dered somewhat transparent by the application of oil to it. Each picture is 

 then to be cemented to a separate plate of glass by means of copal or other 

 suitable transparent varnish, which must be previously applied to the glass, 

 and partially dried attained to the state called tacky. In applying the 

 picture to the glass, care must be taken to press out all the air bubbles 

 between the paper and the glass. Each picture is then allowed to become 

 dry, or nearly so, when it will be well to scrape off the back carefully to 

 remove any excrescences. After this is accomplished, one or more coats of 

 copal or other suitable varnish is applied to the pictures ; when these are 

 dry, the two plates of glass are joined together in such a manner that the 

 lines of the pictures coincide, in which position they are cemented or framed 

 together, and excluded from the atmosphere. 



This is a description of the invention in its simplest form. Different 

 effects may be produced when the front picture only is executed or attached 

 to the plate of glass, and the second one placed some distance behind it so as 

 to correspond with the other. Eine effects are produced by cutting out cer- 

 tain parts of the back picture, thus allowing more light to pass to the front 

 one. Colors may be applied to the back picture only or partially to the two, 

 so that one color on the front picture may have a ground of another color. 

 A back-ground of white light, or reflecting material, placed behind the pic- 

 tures, such as enamelled white paper or a plate of enamelled white china, 

 produces good effects. The back-ground may also be silvered over to pro- 

 duce effects according to the taste of the operator. 



Pictures produced according to this process are called Ilallotijpes. They 

 have an appearance something like wax figures, but on the whole are artis- 

 tic and beautiful. Scientific American. 



A method has recently been devised by Mr. Gill, of Liverpool, by 

 which a stereoscopic photograph can be taken with a single lens, and with an 

 ordinary camera. The observer looks into two mirrors jointed in the cen- 

 tre, raised at each side so as to reflect two figures, and these being opposite 

 the lens, two pictures are taken with one lens. But not only arc the tAvo 

 pictures taken at one sitting, but they are non-inverted, which is also a great 

 advantage obtained by the discovery. 



Transparent Enamel Photographs. A novel and elegant adaptation of 

 the photographic art has recently been brought out in London, and patented 

 under the name of " Transparent Enamel Photographs." 



Transparency is attained by fixing sheets of enamel upon glass surfaces, 

 the two forming one plate. Upon one enamel face the picture is taken, the 

 surface having been rendered sensitive by ordinary processes. Then, when 

 inverted, the glass becomes a ready-made protection for the pictures on one 

 side, and another sheet of glass may be placed at the back or not, at plea- 

 sure. The enamel surface will also take water-colors, and when thus 

 painted, the effect is scarcely inferior to that of ivory. These colors are 



