APPENDIX 



433 



(fig. 244) has an entirely open stage, even the clip for lantern-slides 

 being key-holed on to the front, so as to be instantly removable. 

 A prism fitted on the front erects the image if required, or can be 

 taken off if not wanted. 



The front can be hinged up and a mirror slid in, which changes 

 the lantern instantly from a horizontal to a vertical instrument. 

 The above-mentioned prism, turned on a pivot into another position, 

 now serves to reflect the image on to the screen. 



n 



m 



Fio. 244. Prof. Jackson's Science Lantern 



This arrangement is extremely convenient for demonstrating 

 objects that require to be kept horizontal, such simple experiments, 

 for example, as the arrangement of lines of force shown by dusting 

 iron filings over a magnet are easily shown. 



Such a lantern is also very useful as a substitute for black- 

 board illustrations. A piece of finely ground or smoked glass 

 being laid on the horizontal surface of the condenser, the 

 operator standing in front of the lantern can draw or write at will 

 with a pencil or needle-point, and the drawing is represented on 

 the screen as he proceeds. 



The bar and lens of this lantern can be removed, leaving the 



F F 



