English brewery cask units
Chart

gallon
firkin
kilderkin
barrel
hogshead
-
Year designated
-
-
-
-
1
hogsheads
-
-
-
-
1
​1 1⁄2
barrels
-
-
-
1
2
3
kilderkins
-
-
1
2
4
6
firkins
-
1
8
16
32
48
ale gallons
(1454)
= 4.621 L
= 36.97 L
= 73.94 L
= 147.9 L
= 221.8 L
ale gallons
(1454)
1
9
18
36
54
beer gallons
(1454)
= 4.621 L
= 41.59 L
= 83.18 L
= 166.4 L
= 249.5 L
beer gallons
(1454)
1
​8 1⁄2
17
34
51
ale gallons
1688
= 4.621 L
= 39.28 L
= 78.56 L
= 157.1 L
= 235.7 L
ale gallons
1688
1
9
18
36
54
ale gallons
1803
= 4.621 L
= 41.59 L
= 83.18 L
= 166.4 L
= 249.5 L
ale gallons
1803
1
9
18
36
54
imperial gallons
1824
= 4.546 L
= 40.91 L
= 81.83 L
= 163.7 L
= 245.5 L
imperial gallons
1824

Question: How many ale gallons was hogshead defined as in 1688?
Answer: In 1688 the ale hogshead was defined to be 51 ale gallons (235.7 l).