Equipment of the Class Rooms. 



. :.u,U9 



50119. 1:12. 



50 120. 1 : 5. 



50,119. Suspended Board for the Reflecting Galvanometer, Figure, with niekelled brass 

 rods and polished hoard. Price, without galvanometer 



This suspension device is very practical, as the galvanometer is always ready for use, and cannot 

 be touched. The slit of light formed by a glow lamp filament is projected by the galvanometer mirror 

 on to a scale 4 to 6 m long; the movements of the light pointer can be easily read from the audi- 

 torium. The current is carried by 3 well insulated flexibles on a terminal board on the side of the lecture 

 table. By employing Terminals 1 and 2 the thick windings of the moving coil are put into circuit, 

 and the thin windings are connected up when Terminals 2 and 3 are used. 



. s. d. 

 1. 10. 



50.120. Electric Glow Lamp, on stand, provided with protecting chimney 

 reflecting galvanometers 



(Figure) for 



0. 18. 



The glow lamp is a single filament scale lamp. In ordering the voltage on which the lamp is 

 to burn should be given. If this is not stated, 110 volt lamps are supplied. 



50.121. 7 metres triple flexible cord, 6 porcelain insulators for connections from galvano- 

 meter to lecture table and 1 serpentine slab with 3 terminals 0. 12. 



50.122. Galvanometer Scale, 4 m long, painted on linen, divided into decimeters, with metres 

 figured, for fixing on to wall 0. 12. 



50.123. -- T h e preceding, 6 m long ! 0. 16. 



50.124. Transparent Galvanometer Scale, 2 m long, of ground glass, mounted in wood frame, 

 graduated every 5 cm, with lugs for hanging from ceiling (Figure on p. 21) . . . 0. 17. 



This scale is suspended at a distance of about 2 m from the galvanometer. With its aid it is 

 possible to arrange the galvanometer and scale in front of the audience. 



50.125. Adjustable Ceiling Suspension for Reflecting Galvanometers (F i g u r e), with 10 m 

 copper wire rope, windlass, and 2 rope pulleys, but without galvanometer or lamp . . 6. 10. () 



Between a tall frame composed of 4 metal tubes and wood cross pieces a similar (lower) frame 

 can be adjusted in an up and down direction. With this object the latter frame can be hung upon 

 a copper wire rope which is carried over pulleys to a windlass. 



50.126. Anti-vibration Suspension for Reflecting Instruments (as suggested by J u 1 i u s), 



F i g u r e , for fixing to the ceiling (Zeitschrift fiir Instrumentenkunde, 16, 1896, p. 267) 18 15. 



The lateral vane-shaped dampers are suspended in vessels which are placed alongside the device I 

 and filled with paraffin oil. 



Water Air Pumps and Water Jet Blowers. 



(Aspirators and Force Pumps.) 



The following points should be taken into consideration in selecting the Water Air Pump: 

 For cases in which at least 2 4 atmospheres water pressure is available the pumps suggested 



l>y Arzberger and Zulkowsky should be chosen, these giving in a short time a vacuum up to 20 mm 



mercury. In this pump the water flows through an annular space and sucks the air through a tube 



connecting with the space. 



If no water pressure is available, Bunsen's pump must be selected, this rendering necessary 



a vertical fall pipe of at least 10 m long. 



Cl 52Gt, 3.i. 



