216 APPENDIX. 



18. To find the velocity necessary to discharge a given quantity of water. 



RULE. Multiply the number of cubic feet discharged per minute by 1100, and divide the 

 product by 6 times the square of the pump's diameter in inches. The result will express the 

 velocity of the discharge in feet per minute. 



Example. The diameter of the pump being 16 inches, and the discharge 179 cubic feet per 

 minute, required the velocity. 



16 inches 179 cubic feet 



16 1100 



96 1536) 196900 (128 feet velocity 



16 1536 per minute. 



256 4330 



6 3072 



1536 12580 



12288 



292 



19. To find the diameter of the pump necessary to discharge a given quantity of water. 



RULE. Multiply the number of cubic feet to be discharged per minute by 1100, divide the 

 product by 6 times the velocity in feet per minute, and the square root of the quotient will be 

 the diameter of the pump in inches. 



Example. The velocity being 32 strokes per minute, the length of stroke 4 feet, and the 

 discharge 1 79 cubic feet per minute, required the diameter of the pump. 



32 179 



4 1100 



128 feetper minute 768) 196900 (256; square root of 256 = 

 6 1536 16 inches, the re- 



quired diameter. 



768 4330 



3840 



4900 



PARALLEL MOTION. 



20. The lengths of the beam, radius bar, and link, as in Fig. 4, Plate x. (B) being given, 

 together with the length of the stroke, to find the point E in the link where the piston rod 

 must be attached. 



RULE. Divide the lengths of the beam and radius bar, measured from their centres of 

 motion, by half the length of the stroke. From the square of each of the two quotients 

 subtract unity ; find the square roots of the remainders, and subtract them respectively from 

 the preceding quotients. The numbers so deduced will express the relative proportion 

 between the segments of the link ; and if we multiply each of them by the length of the link 



