[ 462 j 



LXXXV. On the JVbrh performed by Steam- Engines in Corn* 

 iLuU ivilh each Bushel (if' Coals. 



VV E find that the Table given in our nuinber for August last, 

 p. lis, of work performed by the steam-engines in Cornwall, is 

 still misunderstood by some of our readers, as are also the notices 

 on the same subject given in the numbers since published. The 

 first colunui gives the months, viz. August, Sej)ten;;ber, Sec. ; 

 the second contains the number of engines reported in each 

 month ; the third gives the whole quantity of coals consumed 

 during the month by all the engines reported ; the fourth is the 

 sum of the work performed by the engines reported, with o/ie 

 hushel of coals each: for example, in August IS 11, the first 

 uionth reported, ei^kt engines, each using one bushel of coals, 

 lifted 12{),12G,000 one foot high, one-eighth of which quantity 

 is the average work of these eight engines. If the whole quan- 

 tity of water raised one foot high by the whole quantity of coals 

 consumed by the eiglit engines be required, then the number of 

 pounds in the fifth column, which is the Vvork of every bushel 

 (on an average of the eight engines reported), must be multiplied 

 by the number of busliels expressed in the 3d column. Thus in 

 August ISll, the average work of eight engines was i5,7<jO,O0O 

 poimds lifted one foot high by one bushel of coals : and these 

 pounds multi])licd by 23,661 bushels would give for the whole 

 quantity of water lifted one foot high by all the coals consiuued 

 during the month 372,8973360,000 pounds — and so of the rest 

 of the months in the Table: but this would be only an approxi- 

 mation to truth ; for some engines work more days in a month 

 than others, and those as well as the engines consuming the 

 jjreatest or least quantity of coals may chance to be sometimes 

 the better and sometimes the worse engines of the number re- 

 ported. The tlurd column in the Table was no way necessary 

 to its construction ; it was inserted merely as a piece of curious 

 information respecting the general consumption of coals in 

 Cornwall. But, in fact, the title of the fourth column was in- 

 accurately expressed. To save trouble in future references, we 

 again insert the Tabic, but now brought down to November iu- 

 clusive. 



Tabus 



