[1] London Ales.
[2] Strong Burton Mild Ale.
[3] Fairly representative of “Pale Ales.”
[4] Heavy Stock Ales.
[5] Irish Stout.
[6] Nos. 2 and 3 are respectively “single” and “double” London Stouts from the same brewery.
[7] London Porter or Cooper.
[8] The specific gravity, or “gravity” as it is always termed in the industry, of the brewer is 1000 times the specific gravity of the physicist. This is purely a matter of convention and convenience. Thus when a brewer speaks of a wort of a “gravity” of 1045 (ten-forty-five) he means a wort having a specific gravity of 1.045. Each unit in the brewer’s scale of specific gravity is termed a “degree of gravity.” The wort referred to above, therefore, possesses forty-five degrees of gravity. The “original gravity,” it may here be mentioned, represents the specific gravity of the wort (see [Brewing]) before fermentation. The solids in the original wort may be ascertained by dividing the excess of the gravity over 1000 by 3.86. Thus in the case of Mild Ale No. 1 the excess of the original gravity over 1000 is 1055.13 − 1000 = 55.13. Dividing this by 3.86 we get 14.28, which indicates that the wort from which the beer was manufactured contained 14.28% of solids. In the trade the gravity of a beer (or rather of the wort from which it is derived) is generally expressed in pounds per barrel. This means the excess in weight of a barrel of the wort over the weight of a barrel of water. The weight of a barrel (36 gallons) of water is 360 ℔; in the above example the weight of a barrel of the beer wort is 360 × 1.05513 = 379.8. The gravity of the wort in ℔ is therefore 379.8 − 360 = 19.8. The beer which is made from this wort would also be called a 19.8 ℔ beer, the reference in all cases being to the original wort.
[9] A particularly heavy beer, only brewed at certain times in the year.