THE BOOK OF THE LANTERN. 245 



seen in the microscope are by means of opaque objects 

 viewed by means of the spot lens. In like manner we 

 can obtain wonderful effects by the use of the opaque lan- 

 tern. Let me give one or two examples of the use of such 

 an instrument. Suppose that a lecture upon the history 

 and construction of the watch is contemplated. How dull 

 such a lecture would be if illustrated merely by a set of 

 diagrams ! The audience would soon be lost in the maze 

 of toothed wheels and springs, and few would understand 

 the difference between one movement and another. But let 

 the same lecture be illustrated by watches in action, their 

 enlarged images thrown on the screen, and their wheels all 

 at work, and how differently will the audience regard the 

 subject before them. Every tiny screw, the brilliant blue 

 of the steel parts, the very grain of the metal is beauti- 

 fully shown, while the ceaseless and silent working of the 

 mechanism adds greatly to the picture. Coins and medals 

 can also be splendidly shown by the same apparatus, and' 

 far better than in any other way. Various fruits can be 

 shown in section ; a lemon or orange so treated being a very 

 curious object, especially if it be squeezed, when the pips 

 and juice fly upward, or, at any rate, appear to do so. A 

 freshly-opened oyster makes another peculiar object for 

 the opaque lantern. These few examples will show that 

 this form of lantern is one which can be of great use in 

 intelligent hands. It is especially serviceable to the 

 owners of cabinets or collections of curiosities, moths and 

 butterflies, coins, medals, shells, minerals, &c., which 

 cannot readily be photographed, or which it is desirable to 

 show with their natural colouring. 



