1034 SEC. 19. EDUCATIONAL APPLIANCES. 



Balls, of various metals, which pass through a wax plate in times varying 

 as their capacities for heat. 



Faraday's Apparatus, to exhibit convection in liquids. 

 Convection of Heat in liquids ; large size, for the lecture table. 

 Set of Barometer Tubes, to show elastic force of various vapours. 

 Marcel's Steam Boiler, to prove that temperature increases with pressure. 

 Ventilation of Rooms, fitted bottle, to explain. 

 Rain Gauge, simple, to measure fall of rain. 



Light. 



Electric Lamp, source of light. 



Groves Battery, to work electric lamp. 



Perforated Screen, for supporting objects in the ray of light. 



Bottle Prism, for holding carbon sulphide and producing long spectrum on 

 the screen. 



Condensing Lens, to throw enlarged images on the screen or wall. 



Ground-Glass Screen, to receive small images. 



Oxyhydrogen Gas Burner, as source of light. 



Oxyspirit Burner, and lantern, cheap substitute for electric lamp. 



Complementary Prisms of Crown and Flint Glass. 



Oscillating Prism, to produce white light by rapid action on the retina. 



Bun sen and Kirchqjfs Spectroscope, for Spectrum Analysis. 



Set of Lenses, to explain their shape and action. 



Set of Lenses, mounted, with focussing screen to explain their various 

 action. 



Glass Mirror, concave, to concentrate rays. 



Glass Mirror convex, to disperse rays. 



Curved Mirror, showing distorted image. 



Plane Mirror, black. 



Angular Mirrors, double reflection. 



Bunsen's Photometer, to measure lighting power of gas, &c. 



Ritchie's Photometer, for comparing one light power with another. 



Colour Disc, to explain constitution of white light. 



Colour Disc, with series of discs, explaining combinations of colour. 



Colour Top, explaining combinations of colour. 



Norremberg's Polariscope, showing colours through plates of mica, sele- 

 nite, &c. 



Tourmaline Tongs, showing polarised light, in colours, through crystals. 



Newton's Coloured Rings, retardation of velocity of rays. Interference. 



Camera Obscura. 



Screens, dull and bright, to explain absorption and reflection. 



Refraction ; a line or stick appears bent when partly immersed in water. 



Milller's Apparatus, to show refraction in water. 



Stereoscope angle of vision. 



Revolving Disc, to show rapidity of light rays. 



Fluorescence, Uranium-Glass Cube, to produce. 



Fluorescence, Permanganate of Potash, to produce. 



Fluorescence, Uranium Plate, to produce. 



Double Refraction, Iceland Spa, to exhibit. 



Water-Bulb Microscope. 



4O92e. Educational Collection. W. and A. K. Johnston. 



12-inch Terrestrial Globe. 

 Map of New York, Pennsylvania, &c. 

 Illustrations of Natural Philosophy ; 

 sheet 7 steam engines and book. 



Illustrations of Astronomy ; sheet 1 



solar system and book. 

 Geological Map of the British Isles, 



and book. 



