1056 SEC. 19. EDUCATIONAL APPLIANCES. 



4429. Attwood's Machine, with pendulum. 



4430. Gridiron Seconds Pendulum, on stand. 



4431. Mack's Galilei's Fall Kennel. 



4432. Centrifugal Machine, with auxiliary apparatus. 



The construction of the machine is distinguished hy its simplicity. The 

 stand, formed by a cast-iron frame, can be set either horizontally or verti- 

 cally. 



4433. Hydraulic Press. 



4434. Air Pump, with two glass tubes, and Babinet's stop- 

 cock. 



With apparatus : a. Barometer test ; b. Magdeburg hemi- 

 spheres ; c. Mercurial granulation ; d. Globe (recipient) ; c. Elec- 

 tric egg; /. Cylinder for bursting of bladders; g. Freezing 

 apparatus. 



4435. Mach's Wave Apparatus, for illustrating the 

 longitudinal and transversal waves. 



4436. Mach's Apparatus for Sound Reflection. 



4437. Mach's Apparatus for Refraction and Reflexion. 



4438. Mach's Apparatus for demonstrating the Law of 

 Refraction by means of fluorescent liquids. 



4439. Mach's Apparatus for demonstrating the Effects of 

 Lenses. 



4440. Model of a Screw, of wood. 



4441. Model of a Screw, of wood. 



These two models serve for explaining and illustrating to the student the 

 screw motions. One represents a flat, the other a triangular worm ; both 

 serve for demonstrating the longitudinal transverse sections. 



4442. Crown Glass Prism. 



4443. Flint Glass Prism. 



4444. Polyprism. 



4445. Hollow Prism. 



4446. Universal Kaleidophon, for illustrating Lissajou's 

 figures. 



This consists of a thin strip of copper, sliding on a wooden clamp, which 

 may be fastened by a screw to the table, and can be raised to any height 

 desired. 



On the upper part of this strip of copper there is attached a second clamp, 

 through which passes a band of steel terminating at the top in a brad. By 

 means of this second clamp the steel band can likewise be fixed at any 

 desired height. If by pulling with the finger the strip of copper, and in a 

 perpendicular level to the same, the steel band is set into oscillation, the^e 



