BleUrlcal DouUer-^Cofi'efpondmce, i|o« 



With regard to the inflrument itfelf, which is fo truly honourable to the fagacity of Llch- 

 tenberg, Klincock, Volta, and Bennett, but in which my fliare is certainly very trifling, I do 

 not know that its imperfedions are greater tlian was long fince afcertained by the Englifli 

 ele£lricians -, of which an account is given in a paper, at page 394 of the firft volume of this 

 Journal. If Mr. Read is in pofleflion of any new fads refpeding its operation, the public 

 will, no doubt, receive them with as much attention and refpefl:, as they have paid to the re- 

 fults of his former purfults. 



VI. 



Inqmnes refpeEling the CcnflrttB'ton of a Water-wheel, and the ManufaBure of Bricks. 



By a Correfpondent. 



Mr. Nicholfon will oblige a friend to his ufeful Journal, by giving, therein, information on 



the under points. 



December, 1798. 



o, 



'N a ftream where the fall is 61- feet, what diameter ought the water-wheel to be? 



Whether a bucket-wheel, or float-board-wheel ? 



If the former, ought the water to be brought in at the height of the fall; or a portion given 

 for head ? and what portion .? 



Is there any pradical direftion in print, to dired the procefs of brick-making ? 



If there is not, Mr. N. would do a material fervlce to numbers, who are in fome parts of the 

 country, remote from the workmen who are Ikilled in this art, by colleding and publilhing 

 fuch pradical direflions of the nature of the materials and the procefs, as will enable the un- 

 informed to fupply themfelves with this ufeful article. 



The data, refpefting the above-mentioned ftream, are not fufiiciently precife to determine 

 whether a bucket-wheel, or float-board-wheel, would be preferable : the quantity of water 

 aflx)rded per minute ought to have been mentioned. The bucket-wheel appears, upon the 

 whole, to be beft adapted to fmall ftreams of water with a confiderable fall ; but, in contrary 

 circumftances, the clofe breaft-Wheel appears to be preferable, that is to fay, a wheel with 

 float-boards, moving in a channel fo well fitted, as to permit the leaft poflible quantity of 

 water to efcape, without afting upon the wheel. 



The diameter of the wheel may, in theory, admit of confiderable variation. Admitting it 

 to be a breaft-wheel, its radius muft be fomewhat more than the height of the fall. The ve- 

 locity of the furfacc of fuch wheels, as are driven by the gravitating power of water, lies be- 

 tween two feet and fix feet per fecond. Three feet may be confidcred as a good pra£lical 

 velocity, as determined by experience. It is of no advantage, but, on the contrary, a lofs, 

 to confume any part of the head, in throwing the water againft the floats with a confiderable 

 impulfe ; it is only neceflary that the ftream fliould be delivered upon the wheel with fome- 

 what 



