114 Obfervatlons up07i the art of , 



w 



feet fqnare, being a pair to eacK vat, and fufpended otoe at eacli 



end of this beam ; may be compared to a pair of brafs fcales 

 inverted with tlieir beam placed upon a fulcrurr. The poll is 

 fiirnifhed with a pivot at the bottom, tm'ns off in the manner 

 of a crane, and the covers then occupy the interval between the 

 two vats. Thus a line of works may be ere<fted of an indefi- 



^-. 



nite length in zig zag form, with a crane pofl (landing alter- 

 nately between every vat, and the whole to be conne^fted by 



fpouts. ' 



It will at firfl view be perceived, that this piece of machinery 

 is calculated to turn with great eafe and celerity, and it is con- 



ceded tliat a greater extent of works, catv be^covered and un^ 

 covered in a given time upon this, than the former plan j but 

 it is objeded by the advocates of Sear's method, that the fuf- 

 pended weight will derange the pofl, and repairs becorne fre- 

 quently requilite ; that they do not fo efFeclually fecure the 

 vats from rain, and that they occupy more ground than the 

 others. Some gentlemen, however, in whofe hands both m.eth- 

 ods have pafFed the tefl of experience, affiire me, that Kelly's 

 invention deferves the preference, although the difference in the 

 cofl: is eftimated at 7 per cent. In facfl the works upon either 

 plan ai-e completely -imder controul, and require very little 

 manual aid to cover them, when rain is expe(fled. r 



■■ '- a- . ' 



Contiguous to the vats, it^ is neceifary to ere(5l a mill and 

 pump for every 20,000 fuperficial feet of works, ' to complete 

 die apparatus. The |)ump is placed in a fmall cifleni 



funk 



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