Calendar: 1865-1866 Page 542

544 APPLIED SCIENCES vertical is subject to the pressure of water on its vertical face the height of the wall is 12 feet its thickness feet at the top and 10 ft in at the base find where the line of resistance cuts the base the wall being twice as heavy as its own bulk of water 12 Show how to find the specific gravity of substance which is lighter than water by means of Hydrostatic balance Geologist dropped his hammer into stream in taking it up he estimated its weight in water at ounces the head of the hammer afterwards came off and fell into the water and he judged the weight of the handle to be ounces on taking up the head he estimated its weight in water at 11 ounces supposing him to be man of correct judgment find the specific gravity of the wood II -jManufacturtng 8rt antf fHatljtturi Describe the construction of the pumping engines at Camden Hill the arrangement of the valves and the method of working them Compare the efficiency of this form of engine with any other which you may have seen Indicator figure is taken from steam engine give the point of the stroke at which the steam is cut off and calculate the power of the engine How do you determine the point at which the steam should be cut off in the ordinary expanding and condensing engine Describe the methods of preserving timber from damp and from dry rot Describe the construction of the several parts of the Cata- dioptric revolving light as applied to lighthouse purposes and trace the passage of the rays of light from the lamp to the sea Describe the several substitutes for oil which have been proposed as the source of illumination for lighthouses Give the construction of Smith's screw propeller Describe the construction of the bearing for carrying the propeller shaft in the stern of the vessel 10 Describe the construction and action of Morgan's paddle- wheel