438 REVIEW. 



the velocity of spouting liquids (u = 8.02 <x/A). (&.) Why must the 

 unit of measure used with this formula be feet ? (c.) Deduce a 

 similar formula in which the meter is involved as the unit. 



19. Name four kinds of water-wheels, and describe the most 

 efficient of them. 



20. (a.) Explain the action of the mercury barometer, (b.) Give 

 Mariotte's law. (c.) Describe the piston of Sprengel's air-pump. 

 (d.) Describe the ordinary air-pump, (e.) Explain the action of the 

 siphon. 



21. (a.) How would you illustrate the law of magnetic attraction 

 and repulsion ? (&.) Give the theory of magnetic fluids, (c.) What 

 do you think of its accuracy and value? (d.) Explain magnetic 

 induction. 



22. If the capacity of the barrel of an air-pump be } that of the 

 receiver, how much air would remain in the receiver at the end of 

 the fourth stroke of the piston, and what would be its tension 

 compared with that of the external air ? 



23. What is the pressure on the side of a reservoir 150 feet long, 

 and filled with water to the height of twenty feet ? 



24. (a.) Why is a reservoir usually built in connection with 

 water- works ? (6.) Why are fire-engines provided with an air- 

 chamber? (c.) Why should the nozzle be smaller than the 

 hose? 



25. (ff.) Why can you not raise water 50 feet with a common 

 pump ? (6.) What change would it be necessary to make in the 

 pump in order to raise water to that height ? (c.) Illustrate by a 

 diagram. 



26. (a.) Give the law of electrical attraction and repulsion, and 

 illustrate by pith-ball electroscope. (6.) Define conductors and non- 

 conductors, electrics and non-electrics, (c.) Illustrate by an example 

 of each. 



27. (a.) Give and illustrate each of the laws of motion. (6.) 

 Explain composition and resolution of forces with illustrative 

 figures. 



28. (a.) Give the facts of gravity and the law of weight. (&.) 

 If a body weigh 120 Ibs. 2500 miles below the surface of the earth, 

 at what distance above the surface will it weigh 80 Ibs. ? 



29. Explain and illustrate electric induction fully. 



30. (a.) Explain the construction and action of the electrophorus. 

 What kind of electricity is discharged from it ? (6.) Describe the 

 Leyden jar and explain its action, (c.) Explain the action of the 

 plate electric machine, (d.) lu what way do lightning-rods protect 

 buildings ? 



