When I first did some research on the Imperial system of measurement I found it hilarious. I was trying to look up a, "Grain." It turns out a grain is a unit of mass equal to approximately 65mg. It comes from, "The weight of a grain seed from the middle of an ear of barley." The weight of a wheat kernel was considered 45/64 of a grain of barley. As well as being the fundamental unit of mass it's also a third of an inch - an unrelated unit of length. Let's talk about some other units of Imperial measure, but first let me highlight some terms. The system we know as Imperial is comprised of at least three historical systems of mass, and I'll break them down. They're called the Avoirdupois System, the Apothecary's System, and the Troy System. In the Avoirdupois system there are 7,000 grains to the pound, 16 ounces to the pound, 16 drams to the ounce, which makes the dram, the next smallest unit to the grain, a convenient 27 and 11/32 of a grain. In the other direction there is also the hundredweight (100 pounds), and the short-ton (20 hundredweights). In the Apothecary's system, things progress slightly more simply from the grain. There are 20 grains in a scruple, 3 scruples in a dram, 8 drams in an ounce, and 12 ounces in a pound. Of course, they're not even similar weights to the Avoirdupois system. There is, for example, exactly 175/384 of an Avoirdupois pound in each Apothecary's pound. The Troy system has a pennyweight, which is 24 grains, there are 20 pennyweights to the ounce and 12 ounces to the pound. All that's left is a stick, which is a cooking weight equal to 4 ounces. In terms of length, it all starts at the inch, which is three barleycorns long. 12 inches to the foot, 3 feet to the yard, and 5280 feet to the mile, unless, of course, you're a surveyor, in which case you also have the link, which is 33/50 of a foot, a survey foot which is defined as 1200/3937th of a meter, 25 links in a rod, 100 links in a chain, and 80 chains in a mile. The mile and foot work out pretty similar to their archaic counterparts. Then there is the hand, which isn't defined in terms of any other unit. Then there's area! You've got all the standard measures of length squared plus the acre, which is ten square chains. Volume is where it gets fun. Apart from the cubic versions of the above, volume seems to be based on the space taken up by a particular mass of liquid, and so you have a fluid ounce, which is almost, but not quite, the volume that one ounce of water takes up. Then you have the fluid dram, which is 1/8th of that like in the Apothecary's system of weight. The disused minim is 1/60th of a fluid ounce. In the other direction, a gill is 4 fluid ounces, a cup 2 gills, a pint 2 cups, a quart 2 pints, a gallon 4 quarts, a beer barrel 31 gallons, an oil barrel 42 gallons and a hog's head 63 gallons. For liquids. For solids the measure is still based on the volume a certain mass takes up, and so a pint of rice occupies more space than a pint of water. The relationships between the units seem to be the same as in the liquid case, just that the actual volume is slightly different. There are also two additional units, the peck, which is 2 dry gallons, and the bushel, which is 4 peck. Because it is difficult to measure the volume of things like wheat, a bushel is generally defined in terms of weight, and so a bushel of maize is the volume taken up by 56 pounds, and a bushel of wheat 60 pounds. This leaves the bushel in the strange situation of being a measure of weight as well as volume defined in terms of the volume of a weight of a liquid that's not quite water. The real fun is in derived units, and so you can merrily consider density in bushels per bushel. (Mass of bushel per volume of bushel = density). Fahrenheit was constructed so that 0F is the temperature of a solution of ice brine, 32F is the melting point of water, and 96F is body temperature, so that there are 64 intervals between those two unrelated concepts... and the reason Daniel Fahrenheit chose a power of two was so that he could construct the scales on his thermometer by bisecting the lines on his scale 6 times. This made labeling the thing easier. Later on, people came along and said, "That's not useful," and redefined the upper end in terms of the boiling point of water, as 212F. As a result it's even more arbitrary. 0F is now somewhere near but not quite the temperature of that solution of ice brine, 32F is exactly the freezing point of water, 100F is pretty close to but not quite body temperature, and 212F is exactly the boiling point of water. And if you're wondering why body temperature isn't 96F, it's because body thermometers still use the old unmodified Fahrenheit... What.