910 SEC. 18. BIOLOGY. 



3661. Set of Objectives, from 30 millimetres to 0-7 milli- 

 metre focal distance, in all 21 pieces. Some with the correction 

 for cover glass. The whole in case with lock and glass lid. 



C. Zeiss, Jena. 



This collection embraces a complete set of microscope objectives, as contained 

 in the catalogue of the exhibitor No. 21, 1874. Some of them are furnished 

 with an " adapter," so as to suit the length of the tube of English microscopes. 

 The threads are those of the " Microscopical Society's- screw." 



3559. Large Microscope, suitable for any research, with 

 rotating stage, and joint for inclining the body of the microscope. 



JR. Wasserlein, Berlin. 



3560. Small Student's Microscope. 



R. Wasserlein, Berlin. 



3561. Microscope MTo. 1, combined with a photographic 

 apparatus and accessories. Seibert $ Krafft, Wetzlar. 



3562. Microscope No. 3. Seibert $ Krajft, Wetzlar. 



3563. Microscope Wo. 5. Seibert $ Krqff't, Wetzlar. 



3564. Microscope No. 7. Seibert $ Krqftt, Wetzlar. 



3565. Complete Microscope, with Abbe's illuminating 

 apparatus, magnifies from 20 to 1,100 diameters. 



F. Schmidt and Haensch, Berlin. 



3566. Microscope (specially adapted for mineralogical re- 

 search), with polarisation apparatus. Ernst Leitz, Wetzlar. 



Height of the instrument, 1 foot 3 inches. 



There is an arrangement for turning the tube round the optical axis, together 

 with the upper round stage, which is prepared (after the design and drawing 

 of Professor Mohl of Cassel) with a graduated rim. 



The under-stage carries the vernier, and is provided with a circular 

 diaphragm, which, together with the polariser, is furnished with a convex lens. 



The coarse adjustment is done by a rack and pinion, and the fine adjust- 

 ment by a micrometer screw ; with draw-tube, and plane and concave mirror 

 with vertical and horizontal movement. An eyepiece micrometer, the cross 

 lines of which can be easily used for estimating the angle of dichroism, and 

 angle measurement, by holding the eye-piece fast and turning the stage on 

 which the object lies. A revolving nosepiece for holding five objectives. 

 Analyser for fixing to the eyepiece, with a graduated circle. 



A calcspar plate placed between the eyepiece and the analyser serves for 

 the stauroscopic examination of crystals ; magnifying powers 60 to 2,800 

 diameters. 



3567. Microscope, with nine objectives, four eyepieces, 

 and other apparatus. E. Leitz, Wetzlar. 



3568. Microscope, with three eyepieces and four objectives. 



E. Leitz, Wetzlar. 



