Fig. 1. 



improved Instruments of the Camera-Lucida Class. 411 



by any ingenious person ; thus an instrument may be de- 

 vised and readily constructed for any special purpose. The 

 following is a description of the instruments exhibited at the 

 meeting: — 



(1) An ordinary tinted glass reflector for use with the mi- 

 croscope. The tinted glass usually used was replaced by a 

 piece of glass covered with a thin film of silver. The silvered 

 side is turned towards the eyepiece and reflects the magnified 

 image. In this form several reflectors, differing in the thick- 

 ness of the silver film, should be available for regulating the 

 ratio between the transmitted and reflected light ; but a cer- 

 tain thickness of film will be found which is applicable to most 

 purposes ; so that change of reflector is seldom necessary. 



(2) Camera lucida with double 

 reflection (fig. 1). The first re- 

 flection is from a thick film of 

 silver ; the second is from a 

 thinner film. The thickness of 

 the second film may be adjusted 

 as described above. . It will be 

 seen that the plane of delinea- 

 tion is seen through the second 

 reflector, not past it as in the 

 ordinary instrument. In the 

 diagrams the thick oblique lines 

 are the silver films, the thin 

 lines the directions of the light ; 



the arrows the object, and the dotted line the paper on which 

 the object is to be drawn. 



(3) A form of reflecting camera for sketching microscopic 

 objects (fig. 2). This instrument 

 being fitted to the eyepiece of the 

 microscope, the paper and pencil- 

 point under the larger reflector 

 appear in the field of the micro- 

 scope. The object is seen direct. 

 The second mirror in the instru- 

 ment exhibited was an inch square. 

 This instrument may be used with 

 the body of the microscope at any 



angle, it being merely necessary to place the drawing-paper 

 in a plane parallel with that of the microscope-stage. In the 

 figures 2 and 3 the mirrors are represented as parallel ; they 

 should usually be inclined to each other, to increase the dis- 

 tance between the plane of delineation and the object. 



(4) Another reflecting camera for sketching small objects is 



2G2 



