More Weird Units Ride Again


There is a collection of strange and elderly units reserved for measure of volume, particularly of what are called 'dry goods', often meaning originally crops.

Among such units are some that your grandparents and two or three more generations earlier would be familiar with from school, such as the peck, the bushel and the basket. Of course, there are Imperial and an American versions.

Dry Units  start off with the imperial wet units pint, quart and gallon.

pint = 20 fluid ounces (fl. oz.) 

quart = 2 pints

gallon = 4 quarts = 8 pints

peck = 2 gallons        which is 8.809 76754172 litres in the US and 9.09218 litres in Imperial

kenning = 2 pecks    This one is perhaps obsolete, meaning not even used in the US (not USed!)

bushel = 2 kennings = 4 pecks = 8 gallons

firlot = 4 pecks  Firlots mostly known in Scotland to around 1700, where it was defined as 1200 Scottish cubic inches.

A peck is two dry gallons (hence 8 quarts and 16 pints), which is 8.81 litres. I wonder if in the US the metric unit is a liter. In the US, dry measure requires the prefix dry, as in dry barrel, which is different from a fluid barrel such as a beer barrel or an oil barrel.

Dry barrel (defined in wikipedia) This is the US measure. 7056 cubic inches, which is 4 ¹/₁₂ cubic feet, 26¹/₄ gallons, except for cranberries, which are 5826 cu. in. Some dry goos have defined weights to constitute a barrel, such as cornmeal (200 pounds), salt (and lime for cement) 280 pounds; some are defined in cubic feet (5 cu.ft. to a barrel of sugar)

UK Imperial barrel = 36 gallons. Exceptionally, this is 224lbs for cheese or butter, making ten barrels of cheese to the ton and a barrel is then two hundredweight, 2cwt.

Wet barrels

The UK is consistent, and a wet barrel remains 36 imperial gallons.

In the US most fluid barrels (apart from oil) are 31.5 US gallons (26 imp gal; 119 L) (half a hogshead), but a beer barrel is 31 US gallons (26 imp gal; 117 L).  (wikipedia). An oil barrel is defined as 42 US gallons (exactly), which is about 159 litres, or 35 imperial gallons.

The British have a long history of drinking beer in volume and so understandably have specialised words and units. In beer, the barrel at 36 gallons (288 pints of beer before counting losses) was the smallest of a set of barrel-shaped containers. Counting in gallons:

Tun = 252; Pipe or Butt - 126; puncheon or tertian = 84; Hogshead = 63; Tierce = 42, Barrel = 36.

However, there were changes made several times in history, such that the barrel has been 32, 34 and 36 gallons. The hogshead was, for a while, 54 gallons. Imperial units were defined in 1824 in the UK (and thus the whole Empire).

Going downwards from a barrel, is the firkin,  quarter barrel originally but kept at its previous size in 1824, such that a firkin is recognised a nine gallons, not the eight you might have expected. Modern beer is delivered in firkins, so what you recognise as a modern beer barrel has 72 pints of liquid, of which usually 66 are saleable, much nearer the 8 gallon original. So, in effect, the modern firkin has 8 gallons (64 pints) of saleable beer, plus a few apologies. A pin is exactly half a firkin, 4.5 gallons, 36 pints and this is the unit you might buy to drink or brew with at home.

In wine, the barrel shapes have the same names and relative sizes, but a wine gallon as defined in the reign of Queen Anne (1707 specifically) is the unit that carried off to the Americas. Thus the number of gallons above is still correct above, i.e., Tun = 252; Pipe or Butt - 126; puncheon or tertian = 84; Hogshead = 63; Tierce = 42. But the gallon itself is a different size. So in a sense it would be true to say that the US barrel is based on the wine barrel while we're not talking about oil, while the Imperial (British, to some) barrel is that of the beer.

Fluid gallon (Imperial) = 4.54609 litres Please note that this is not exactly the same digits as for grammes in a pound (mass), which is 453.59237. To 3 sig fig they are both 454 (ignoring the decimal point). The reason they are so close is to do with changes in definitions. There was a point at which a pint was 20 ounces = 1¼ pounds, but the fluid ounce underwent some more precise definition, which stopped this convenience. For school, one can usefully remember 454g = 1 lb, as it says on any old jamjar, and that a gallon was 10 lbs of water, so it should have been (very close to) 4.54 litres

Fluid gallon (US) = 3.785411784 liters  (litres)    also 231 cubic inches. 

Now 231 is a peculiar number, 3x7x11.


If and when you meet Americans, they will not automatically understand your use of any metric unit. If you use the words they expect such as inch, foot and yard, you will hit problems as soon as you have any need at all for precision. In volume they use gallons and quarts — the preferred dairy unit is quart, for milk, yoghurt and ice-cream—but these are not quite the same as we use. It would be useful to remember that the UK unit is bigger by roughly 20%.

Exercise. This is not any sort of a test but if your ability to read and subsequently do arithmetic with that content.

 The Scots had a number of odd units of dry volume.  Assume that a firlot and peck were much the same as in England Add to that knowledge: a boll (pronounced as in bowl) as 4 firlots;  a chalder which varied with the grain being measured, possibly the same as a chaldrom in England, mostly used for coal; a forpet (also a lippie, from the Scots for a basket, a leap) was a quarter of a peck.

1 Express a forpet or lippie is English gallons.

2. Describe that forpet basket if it is much the same sort of shape as the bushel basket, roughly cylindrical, depth around half the diameter. Show how you reached your answer.

3. A boll sounds like quite a large vessel. Again, put that as gallons and rough out the dimensions if the radius is the same as the height. To the nearest inch will do, even if you're using centimetres. Show how you reached your answer.

I was wondering about our various dustbins. Councils in Britain generally use sizes of 120litres and 240 litres, thought there are some very large bins at 360 litres. The much smaller circular style that you would find at a hardware store is 90 litres.

4. Express the 90 litre dustbin to the nearest firkin.

5 Express the smaller council bin in integer firkins. This is close to one (unity) in one of the US measures.

6 My green bin, intended for garden waste, is a 240 litre vessel. If it is filled with dry goods, express this in the most suitable large unit.  If it was filled with beer it would be very heavy, at around 250 kg, but would also equate to one of the large beer units.

7 Commercial premises use bins with four wheels at volumes of 500, 660, 770 and 1100 litres. Put these in order, along with the biggest of the household bins. Match them up with the tun, butt and puncheon and decide which is closest.


8  Express the UK gallon as a percentage of the US gallon to as many figures as you calculator will provide, and then (testing your grasp of representation) in these four forms:

 6 s.f.,    4 s.f.,,      3 s.f.  and     2.s.f..

9  A Chevrolet big-block engine could be any of several sizes between 348 and 632 cubic inches ( Three of these sizes work out to metric capacity to the nearest half litre. They are the 366, the 396 and the 427 sizes. Convert to litres. A Rolls Royce Phantom is available in the US at 6.7 liters (litres). What do you think the equivalent volume is to the nearest cubic inch? Show how you did the conversion.

10 You don't really want a tenth question. I have a friend who is a pretty senior engineer for Caterpillar. They make large diesel engines which they sell as units; I found catalogue (US catalog) sizes in cubic inches, they call the 220 cu. in. engine a C3.6), the 268.5 they call a C4.4. What then do you think the size of the C32 is? Give an answer to an American that doesn't travel, to the nearest integer. 

Suppose one of their engines was a cubic foot in capacity. What do you think they would call this engine? The off-road truck shown is around this engine size.

Q4 90 litres is 19.8 gallons. A firkin is nine gallons, so the hardware store bin is two firkins. 2.2 to one more significant figure.

Q5 120litres is 26.4 gallons so close to three firkins, very close to a US dry barrel.

Q6 240 litres is  63 gallons. 64 gals would be 8 bushels.  This would be not quite two barrels  (1.75 x 36 litres = 63 litres)     In Scotland this bin would be close to a whole boll in Scotland. If it was filled with beer, it would be a whole hogshead.

Q7 1100L = 242 gals = 0.96 tun. 770L=2.01 puncheons. Somewhere between the 660L and 500L is a Butt and the 360L - 80 gals = 0.95 puncheon. So the biggest is closest to a tun, while the 770L is closer still to exactly two puncheons.

Q8 1 UK gallon =  1.2009499255 US gallons  1.20095 US gallons (6sf) = 1.201 US gallons (4sf) = 1.20 US gallons (3sf) = 1.2 US gallons (2sf). So % answers are 100 times bigger. The UK gallon is 20% bigger than the US gallon.

Q9 6.7L = 409   348 =5.7L; 366 =6.00L; 396 =6.5L; 427 =7.00L; = 10.35L   6.7L = 409 which is one of the given US engine sizes.

Q10 The Caterpillar Csize is in litres (I blame my pal; living outside the US has an effect if you want to sell stuff). The C32 is a 32 litre engine, 1959 in³.  A cubic foot, 1728in³, is 28.317 litres, so they'd call it the C28 or the C28.3.

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