No. 62 756. 



Dynamos. Explanatory Models. 



989 



62 741. 1 : 5. 



62 753. 1 : 4. 



62 754. 1 : 12. 



62 755 A. l ; in. 



62 755 B. 1:20. 



62.750. Iron Ring with a group of wire turns and commutator for explaining the s. d. 

 Gramme Eing 1.12.0 



62.751. Gramme Ring with 12 groups of turns and commutator in 12 parts .... 2. 2. 



62.752. 3 Drawings for explaining Nos. 62,750 and 62,751, on cardboard 0. 3. 



62.753. Model of a Dynamo with Gramme Ring, Figure, constructed of wood and metal; 

 cannot be worked; for explaining construction only 1.10.0 



62.754. Apparatus for explaining the Direct Current Machine having Ring Armature, after 

 Pfaundler, Figure, very large model of wood and pasteboard; cannot be worked 2. 0.0 



62.755. Apparatus for Demonstrating the Passage of the Current in the Gramme Ring when 

 Direct, Alternating or Three-phase Current is taken off; after Hammerl, Figures A 



and B (Ztschr. f. d. phys. u. chein. V. 9, p. 33), with 10 discs; cannot be worked . 4. 0. 



The apparatus consists of a firmly fixed round glass disc having an axis in the centre for a movable 

 glass disc of the same size. Pasteboard discs with a drawing ot the Gramme Ring can be placed on the 

 latter disc corresponding to the various cases. The windings and commutator segments are cut out and 

 transparent coloured silk paper is pasted on behind, so that by using a black pasteboard disc cut out in lines, 

 ;md covering the fixed glass disc, luminous points occur (by illuminating by means of a powerful source 

 of light set up behind the apparatus) which are displaced when the movable disc is rotated and in this 

 manner render visible the course of the currents. 



Fig. A shows the apparatus set up with a pasteboard disc, while the remaining 9 pasteboard discs 

 are illustrated in Fig. B. 



Cl. 3817, 2704, 



2795, 2706, 2707 



