TEACHING APPARATUS. 1029 



Holdat's Apparatus, for proving that the pressure depends on the height 

 of the column and the area of the base, and not upon the capacities of the 

 vessels. 



Glass Cone with movable base for determining the pressure on the base of 

 a cone, having a movable bottom. 



Apparatus to prove that water presses equally in all directions if pressure 

 be applied to any part of it. 



Hydrostatic Bellows, for lifting a heavy weight by the pressure of a 

 column of water. 



Br amah's Hydrostatic Press, glass model. 



Bramah's Hydrostatic Press, metal model of some power for school use. 



Force Pump of Glass, with glass valves and pistons, to facilitate inspection. 



Lift Pump of Glass, with glass valves and pistons, to facilitate inspection. 



Fire Engine, tin-plate working model of, with double barrels and air cham- 

 ber. 



Hero's Fountain, in which the water jet is caused by the water column 

 compressing the air. 



Fountain, intermitting, glass model. 



Spring, intermitting, glass model. 



Syphon containing a fountain, glass model. 



Appold's Centrifruyal Pump, which raises water by the rapid rotation of a 

 small water-wheel. 



Archimedean Screw, glass model, to raise water. 



Set of Glass Tubes, to exhibit the rise of water by capillary attraction. 



Simple Glass Vessel to prove that water rises to a level in all communica- 

 ting vessels. 



Vessel to show that water rises to a level in all communicating vessels, 

 superior construction for the lecture table. 



Water Wheels, Set of Models, showing Overshot, Undershot, and Breast 

 Wheels. 



Physical Apparatus. Cheapest Set of Physical Apparatus 

 for use in Elementary Schools. Prof. Balfour Stewart's set of 

 apparatus, described in his Science Primer, No. III. 



Description of Apparatus. 

 No. of 

 Experiment. 



1,2. Tin pan, with peas. 



3. Iron plate with four strings. 



4. Balance to carry 2 Ibs. in each scale ; beam two feet long. 

 Piece of metal weighing 200 grains. 

 Set of weights, 600 grains to ^ grain. 

 5. 2 Ibs. mercury in a bottle. 



Two pieces of glass two inches square. 

 6. Apparatus unnecessary. 

 9, 10. Beam of wood. 



Two 4-lb. weights. 

 15. Plumb-line. 



Stoneware dish for mercury. 

 16. Tube for showing level of water. 

 17. Metal cylinder with two tubes and stoppers. 

 Tube with movable bottom and cord. 

 Water -jar for tube. 

 Indigo solution. 

 18, 19. Substance weighing 1,000 grains, same specific gravity as water. 



