The analizer forms part of an ocular which fits into the tube of the microscope and is provided with a graduated disc and index. It is fixed in any desired position by means of a thumb-screw. The polarizer, when used in connection with stands fitted with a substage condenser and iris-diaphragm, is hung in the carrier of the iris diaphragm; when used on other stands it takes the place of the cylinder diaphragm, and if desired may be furnished with a condenser. Price =22.--= 145. =Simpler Polarizing Apparatus.= The analizer is without an ocular and has no graduated disc. The polarizer is as described above =14.--= 146. =Gypsum= and =Mica plates= set of 8 =6.--= 147. =Coverglass Tester=, for measuring the thickness of coverglasses =3.75= 147a. =Coverglass gauge=, dial form, for the rapid and accurate measuring of coverglasses, thin plates etc. A slight pressure on a lever opens a pair of steel clips. The exact thickness is at once indicated by a pointer moving over a divided circle on the lid of a metal box. The gauge measures 0,01 up to 5 mm =12.--= 148. =Nose-piece= for two objectives--Double nose-piece =6.--= 149. =Nose-piece= for three objectives--Triple nose-piece =8.--= 150. =Nose-piece= for four objectives--Quadruple nose-piece =10.--= Nose-pieces can be adjusted to our stands at any time without charge. 151. =Iris-diaphragm= =6.--= [Illustration: Illuminating Lens No. 152.] 152. =Illuminating Lens on stand=, 100 mm diameter =12.--= 153. =Illuminating Lens on stand=, 60 mm diameter =8.--= 154. =Glass slides=, hollow, per doz =--.75= 155. =Glass slides=, English form 3×1", of plate-glass with polished edges, per gross =1.--= 156. =Glass slides=, with well, for moist chambers =--.40= 157. =Cover-glasses=, squares, 15×15 mm, per 100 =--.60= 158. =Cover-glasses=, squares, 20×20 mm, per 100 =--.85= 159. =Cover-glasses=, circles, 15 mm diameter, per 100 =--.85= 160. =Cover-glasses=, circles, 20 mm diameter, per 100 =1.--= [Illustration: Turn-table No. 161.] 161. =Turn-table=, for ringing, with adjustable slide clips =4.--= 162. =Thickened Cedar Oil= for oil-immersion lenses, 1 oz =--.40=