REINICKE^ '' Z. NEUERN MIKROSKOPIE." 293 



for general use by ISI. Reinicke is constructed on the prin- 

 ciple of one constructed on a larger scale by Mr. Andwith^ 

 and with which most persons are, doubtless, familiar. 



Polarization of the light in this form of apparatus is effected 

 by its repeated reflection at an angle of 36° from the surfaces 

 of numerous super-imposed pieces of glass, or by its trans- 

 mission through similar pieces placed in the proper angle. 

 As is w'ell known, many pleasing experiinents in polarized 

 light may be thus performed at a veiy trifling cost. 



Taking advantage of the same principle, M. Ueinicke has 

 contrived a polarizing apparatus, which can be adjusted to 

 almost any microscope, made by any one gifted with the least 

 ingenuity, and at a very trifling cost, and which yet, accord- 

 ing to what he says, is capable of performing nearly as well 

 as NichoFs prisms, and better than polariscopes made of the 

 still more expensive tourmaline. The polarizing medium is 

 constructed of super-imposed pieces of thin covering glass, 

 contained in a square tube of card board ; and the following 

 directions are given for its construction : — 



1. Procure from fifty to sixty pieces of thin covering 

 glass, of uniform size, and a little more than half as long again 

 as they are wide. A convenient size, he states, is 18 -h 12mm. 

 These are to be carefully selected as free from veins or specks, 

 and they should, of course, be as flat as it is possible to pro- 

 cure them. The case or tube, in which they are fixed at an 

 angle to the axis of the tube of 35° 25'', is conveniently made 

 of cardboard. 



On a piece of this material draw the figure shown in the 



r.ccompanying woodcut, which represents the four sides of the 

 rectangular tube. These sides, it should be remarked, are not 

 all of the same width, a, k, i, b, and c, h, g, d, being somewhat 

 narrower than the other two. 



