8CIOPTICON MANUAL. 131 



as a magic lantern, I very much preferred it on this 

 account, to the more troublesome lime light. Its con- 

 venience recommends it as an adjunct to the school-room 

 and I found that very many of the most interesting ex- 

 periments in physics, usually shown in a lantern, can be 

 readily performed with the Sciopticon. My good friend, 

 Prof. Henry Morton, of the Stevens Institute of Tech- 

 nology, in Hoboken, has already described many of these 

 experiments in your manual. I have told you how I 

 have repeated many of them with very little expense 

 in the way of apparatus, and I would now suggest to the 

 would-be purchasers of your lanterns, that should they 

 desire to use it as an adjunct to the lecture table, they 

 need not be alarmed at the expenditure needed to pro- 

 cure all the fixtures required to perfect it. One of the 

 chief pleasures in its use is in the improvising of what 

 is needed. Those who have long purses may prefer to 

 purchase all needed pieces of apparatus, ready-made to 

 their hand, but a few hints may serve to show how they 

 can, with very little skill, prepare what will answer their 

 purpose. As an illustration, let me recall the very pretty 

 experiment usually called the broken arrow, which is 

 shown to illustrate refraction. As an object in the lan- 

 tern, a brass plate having an arrow-shaped opening in 

 it (procurable at the instrument makers) is put in place, 

 this throws upon the screen a white arrow on a dark 

 ground ; now, if in front of the brass plate a strip of 

 thick glass, narrower than the length of the arrow, be 

 held parallel with its surface, no distortion of the arrow 

 image will be seen; but if the glass be inclined so that 

 the rays of light pass through it obliquely, a piece of 

 the arrow will seem to be cut out and be moved to one 

 side. This is a striking illustration and can be impro- 

 vised quite readily, as follows : Procure some slips of 



