1844.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



157 



Fig. 3. 



TABLE. 



From the Table the following resitlts are obtained. 

 The quantity of steam required for one revolution of each piston 1944-2 

 cubic inches. Distance the centre of pressure of the piston travels in one 

 revolution, 10065 feet. Average effective pressure on the piston, 10801b. 

 Greatest expansion 222,0 times. 



Number of pounds raised one foot high by the revolution of one piston, 

 10,980. 



Momentum of one piston .. 10,980 lb. raised one foot high. 



Number of pistons .. .. 4 



Momentum of one revolution .. 43,9201b. raised one foot high. 

 Number of revolutions per.minute 50 



Momentum per minute .. 2,19(1, OUOlh. raised one foot high. 



Deduct for friction say lOpercent. 219.600 



Effective momentum per minute 1,976,400 lb. raised one foot highj 

 1,976,400 



33,000 



59-9 horses power. 



Cubic In. 



1944-2 



4 



7776'8 

 SO 



The quantity of steam consumed by a revolution of one ptston 

 Number of pistons .. .. .. •■ 



iSieam required for one revolution .. .. •. .. 



Number of revolutions per minute .. .. .. .. 



Steam consumed per minute .. .. .. .. 388840'0 



Steam atSOlh. pressure on the square inch above the atmosphere, is 609 times 

 the volume of the water of which it was generated, therefore— 



3^8840 



^-^-Tjr^ = 638-5 cubic inches, ot 37 cubic feet quantity of water evaporated 



for steam per minute. 



In a common double acting condensing engine of the same power, the 

 cfit'ctive momentum will be the same on 1976400 lb. raised one foot high per 

 minute, and if we take Tredgold's data that the eflective power is "63 of th» 

 power of the steam, it will stand thusi 



1970400x100 „,„,, „„ . , .... 



^7. = 313a 13 lb. raised one foot higti 



