David Booth 
Art of Brewing 

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The reverse of this comparison is equally easy. Thus, suppose we have a wort which shows a specific gravity of by the common hydrometer; and we want to know how many pounds heavier a barrel of such worts is than a barrel of water: we seek, in the body of the table, for the nearest number to which we find to be This sum is in the column headed 4, in the horizontal line with the left-hand margin 39; and therefore is the weight sought for.