Capacity

The main dry volume measure used in British recipes are teaspoons (tsp.) and tablespoons (tblsp.)

Beer casks used to be made out of wood. The pieces of the sides are called staves.

How you order beer in Australia

These measures are not only different sizes to the British units of the same name, but different to each other. The wet U.S. units are 86% of the dry U.S. units with the same name. They are both smaller than the British units. The U.S. wet unit is 83% of the British unit, and the U.S. dry unit is 97% of the British unit. So if someone from the UK buys a gallon of gas in the United States, he will only get 83% of what he thinks he will get. While an American will probably flood the forecourt of the British filling station!

I was particularly worried about the American habit of using volume for measuring ingredients for cooking, i.e. they use cups (or half-pints) rather than pounds as the British do (or rather we are now starting to use kilos). We need scales, but at least weight is well-defined! My problem was: Is there a 'dry' cup as well as a 'wet' cup, and are they of different sizes? (There was a subsidary question as to whether butter and cream and peanut butter were wet or dry, and was there a difference between double cream and single cream?) I have had several very interesting comments on this, varying from "Of course we only use one cup" to "Of course we use two cups!" And most people point out that the volumes of butter are marked on the side of the pack (well, so there are in Britain sometimes, but I've usually already started the pack of butter when I come to use it for a cake!) However, eventually one correspondent said that there ARE two types of cup. They vary in design to make it easy to measure wet or dry ingredients, but they are the same size. They are all 8 fluid ounces. This sounded as if it answered all questions, so I checked it out. It seems that the cup used for measuring is a 'wet' cup, and there is no cup measuring half a dry pint. The dry measures of volume seem to be mostly used for amounts greater than a pint (if we ignore spoon measures). The name 'pint' and 'quart' are used in both systems (and are different sizes, so watch out!) However, there is one peculiarity. One reference work described 'fluid ounces' and 'dry ounces'. But here the 'dry ounce' was a measure of weight and the 'fluid ounce' was a measure of volume. In fact, this went on to say "Measures are classified as either dry measures or fluid measures. Fluid measures are measures of volume, while dry measures are measures of weight. Whether the ingredient you are measuring is dry or fluid really doesn't matter, and will only confuse you. Simply use the measure that is specified in your recipe." So you use a wet measure like a cup to measure flour! I like the comment "Simply use the measure that is specified in your recipe" since the words 'pint', 'quart' and indeed 'ounce' occur in both wet and dry forms. At least one reference work used 'ounce' when they really meant 'fluid ounce'.
Another correspondent says "Dry measure is actually little used in the U.S.  A cup of flour or a cup of milk in a recipe are measured in the same measuring cup.  Unless specified otherwise, all measurements are struck even with the top of the container.  The only survival of the identically named and slight differently sized dry units is that they are the officially sanctioned units for the purchase of fresh fruit, like buying a pint of strawberries.  Most people are completely unaware that a pint of blueberries isn't the same pint as a pint of milk." 
Another correspondent has made the following points: "Some ingredients will differ in weight if loose or packed, so a recipe will further specify if the ingredient is to be packed or loose.  When not specified the usage is to pour the ingredient into the measure until the desired level is reached.  Sometimes a note tells the cook not to shake or pack, but this is considered unnecessary.Nuts can be whole, broken, ground etc.  Each form will have a different weight for a given measure, but for the purposes of a recipe that is irrelevant. " (I disagree with him there I think the weight of nuts matter more than their volume!) "Measuring in this manner has an ancient history.  In Ali Baba & the Fourty Thieves a volume (wet) measure was used to count gold coins :)"
I still think the British method of weighing ingredients is better. I'd prefer to weigh gold coins to measuring them by volume!

Still, I would like to thank all my correspondents for illuminating me on this important subject, even if you confused me horribly en route!

A further comment: "One thing I'm surprised you didn't mention is that, while UK volume measures are based on water under specified conditions, liquid and dry volume measures in the US are all based on the cubic inch. They were originally based on the volume of cylinders of specified dimensions, but early in the Nineteenth Century Congress standardized on a gallon of exactly 231 in^3 and a bushel of exactly 2150.42 in^3."
I didn't mention it as I didn't know it!

However, another correspondent, reading the above, says "As I learned this rhyme it is 'A pint's a pound the world around.' This is a mnemonic to help remember the number of ounces in a pint. That is, there are the same number of liquid ounces in a pint as there are (weight) ounces in a pound -- i.e. 16. It is not about the weight of a pint of anything. I suppose people found it easier to remember ounces in a pound." However, it doesn't explain why it's "the world round" since the British pint has 20 ounces! Also it's not a very good mnemonic, since it seems that people misunderstand it.

Another correspondent from Australia says "When my mother taught me to cook, she used, as a rough rule of thumb, one pound of sugar to one pint of vinegar when making chutneys, relishes, pickles and ketchups; and when making jam, one pound of sugar to one pint of cooked fruit." That seems very sensible!

An English correspondent says "With regard to pint measures and mnemonics, I was always taught that 'a pint of water weighs a pound and a quarter'. As you mention, a pint of water actually weighs 20 oz so this works. I have never heard before the one about 'a pint's a pound the world around'." Well, it doesn't in the UK! I must admit that I hadn't realised that a fluid ounce of water weighed an ounce. But it is very close: 1 fluid ounce (of water) weighs 28.35 gram and an ounce is 28.375 gram. The correspondent goes on to say "As a small boy during holidays in Cornwall in the late 1960s, I remember often being sent to the village shop by my grandmother for 'a gallon of potatoes'. Those were the days..." That certainly is a new one on me! I wonder what the shopkeeper said. (British potatoes were always sold by the pound, or even by the stone).
Another correspondent explains this: "The story given me was that during the war years (WWII), when all the brass weights (along with the church bells) went to become shell cases, the villagers bought their potatoes in the ubiqutious galvanised bucket - which held two gallons of water and weighed about a stone (14 pounds) if I remember rightly!  It carried on after the war years because it took time to get the brass back and people had become used to it."

Remember that British Imperial units of volume are different to American units. See above for details.

I find many Imperial to Metric conversions very irritating, because they are far too precise. So here are some rough conversions which you can carry in your head.

"A litre of water's a pint and three quarters." Or, of course, anything else. (It rhymes to help you remember it).

A half litre is definately less than a pint. A quarter litre is less than a half pint. While the British don't mind buying their petrol in litres, there was (and is) considerable opposition to drinking metric beer or milk!

5 litres is more than a gallon. 4 litres is just over 7 pints.

5 ml is a teaspoon. It gets used for medicine.

If you want an accurate conversion: