1032 SEC. 19. EDUCATIONAL APPLIANCES. 



Henley's Universal Discharger for passing charges through an insulated 

 body. 



Hand Discharger with insulated handle. 



Luminous Flash to show discharge in varmo. 



Cheap Electroscope of large size for lectures, a woodeii lath supported on 

 a nask. 



Set of Bells to be rung by the electrical discharge. 



Pith Balls to dance under an excited beaker. 



Cheap Conductor, a tea-tray supported by a beaker. 



Pith Ball Electroscope. 



Gold Leaf Electroscope with condensers. 



Gold Leaf Electroscope without condensers. 



Vulcanite Electrophorus which gives off sparks when excited by friction. 



Glass Hod half roughened to show the two kinds of electricity. 



Rod of Sealing Wax for excitation. 



Rod of Vulcanite for excitation. 



Rod of Shellac for excitation. 



Rod of Sulphur for excitation. 



Fox's Brush for exciting electricity. 



Cats' Shin for exciting electricity. 



Pneumatics. 



Air -Pump y double barrelled, arranged for rapid action, with an auxiliary 

 Tate's air-pump to obtain a very perfect vacuum. 



Tate's School Air-Pump ; this produces a good vacuum quickly, and is 

 made at a moderate price. 



Exhausting and Condensing Syringe. 



Leslie's Apparatus for freezing Water over sulphuric acid in vacuo. 



Apparatus to show that a Guinea and a Feather fall in vacuo with the same 

 velocity. 



French Tube Form of Guinea and Feather Apparatus. 



Apparatus to explain the Barometer and the pressure of the atmosphere. 



Apparatus to cut an apple in half, by the downward pressure of the 

 atmosphere. 



Apparatus to prove that combustion cannot take place in vacuo. 



Heavy Lead Weight which is raised by the expansion of some air contained 

 in a bladder. 



Magdeburg Hemispheres for showing that the pressure of the atmosphere 

 is about 15 Ibs. on the square inch. 



Mercury Cup, in which the pressure of the air forces mercury through the 

 pores of wood. 



Marriotte's Apparatus, to show that under the pressure of two atmo- 

 spheres, air is compressed into half its ordinary bulk. 



Marriotte's Apparatus, for experiments under the pressure of half an 

 atmosphere. 



Lead Weight supported by the upward pressure of the air. 



Fountain in Vacuo, the water being forced up by atmospheric pressure. 



Series of Globes to raise water by the alternate expansion and compression 

 of air. 



Apparatus showing expansion and compression of air. 



Rubber Balis which expand and contract under varying pressure. 



Diving Bell, working model of. 



Pair of Water Bottles, the expansion of the air forces the water from one 

 bottle into the other, and the pressure of the atmosphere causes its return. 



Tantalus Cup. 



