=Glass compressor= with graduation =--.80= =Glass compressor= without graduation, per pair =--.40= =Demonstration microscope.= [Illustration: Demonstration microscope with condenser.] 30a. Adapted for low and medium power. Square stage with wheel-diaphragm. Adjustment by sliding tube; after being adjusted the tube may be fixed by a ring clamp. Detachable handle. With clip to hold a sketch or label, etc. Stand without objective and eye-piece. =6.--= 30b. =The same= with objective 3 and eye-piece I, magnifying 60 times =14.--= 30c. =The same= with adjusting screw for focussing high power objectives, with condenser and iris-diaphragm, without objectives and eye-pieces =18.--= 30d. =The same= with objectives 3 and 6 and eye-piece I. Magnifications 60 and 255 =38.--= [Illustration: Nebelthau's Sliding Microscope.] =Nebelthau's Sliding Microscope.= (Cf. Zeitschrift für wissenschaftliche Mikroskopie, XIII, 1896.) 31. The sliding microscope is an instrument by means of which very large microscope sections, as, for example, large sections of the brain, can be systematically examined. It is also of service in looking over plate cultures of bacteria. The microscope is carried on a heavy beam supported by two stout pillars under which the stage moves. The various movements are accomplished by motion of the microscope on a lateral track upon its support and by motion of the stage on a similar track at right angles to the first. The motion of the microscope is by means of a screw, that of the stage by double rack and pinion. The extent of the movements is indicated in each case by a scale, thus permitting the systematic examination of the entire specimen. The stage consists of a glass plate, measuring 16×20 cm, which is carried in a frame supported on four columns. The tracks permit a motion of the microscope of 18 cm and of the stage of 13,5 cm. A mirror under the stage affords ample illumination. The microscope tube is so arranged that it can be easily removed from the stand and a simple lens substituted for it. The coarse adjustment of the microscope is by rack and pinion. A screw above the objective serves for fine adjustment. The price of this sliding microscope, without objectives or oculars, but with a lens holder and simple lens magnifying eight diameters is =80.--= =Flat glass dish= of the same size as the stage to hold very large sections for the purpose of examining them while in clearing fluid =1.25= [Illustration: Dölken's Microscope stand.]