See this thing?
Supposedly, it's from an antique shop and was a shipping barrel for wool. (Here's the original blog, if you care to read.) It's HUGE!
Why am I looking at this photo? Because a friend of mine was reading a book, where it calls for "5 barrels of wool for winter spinning." She wanted to know much wool a barrel could contain. And frankly, I got a bit curious.
Now, back in the "old days", wooden casks (or what we call barrels today) were used to ship everything from dry goods to liquid goods. Why? Because one man can roll a wooden casks on skids, versus carrying a box of equal weight without assistance.
(Warning, major geeking ahead). I did some searching on the Internet regarding how much a wooden casks actually weighed. It turns out there were several sizes of wooden casks and their measurements are more towards liquid versus the actual volume of measurement, but they were used to carry everything from liquids (beer, ale, rum, etc) to dry goods (nails, apple, tobacco, wool, etc). 
It turns out that each of these wooden casks was a specific type of measurement. A "barrel" was used as a unit of measure equal to 32 gallons. There were other wooden casks (a tun) that held up to 256 gallons of liquid weight! Now, the picture above looks more like a "tun" versus a "barrel", but lets assume "barrel" for now.
Obvoiusly, the dry weight of something is different from the liquid weight. For example, when a hogshead was full with tobacco, it weighed about 1000 lbs . But luckily, the Internet is full of wonderful things, and I found a nifty calculator that converts volume to actual weight, and actually allows you to specify the type of material, including wool!
Now assuming that this calculator is correct AND assuming you can fill every single square inch of a barrel with wool, a barrel volume of 32 gallons is about equal to 350.91 lbs of wool.
Consequently, my friend's book mentions 5 barrels. So, if it truly meant a "barrel" (as in the unit of measurement), then 5 barrels is about 1754.55 pounds of wool. (350.91 lbs x 5 barrels)
And I'm not even about to discuss whether the wool contained in these barrels are processed wool or raw fleeces filled with lanolin...it's still a crapton of wool regardless.
However, lets go back to that photo above. If that wooden cask is the actual size of casks used to ship wool, it looks more like a "tun" versus a barrel. And, again, that handy dandy internet calculator tells us that 256 gallons of volume is equal to about 2,807.26 pounds
Now, multiply that by 5 casks = ~14,000 pounds = 7 tons.
Regardless of whether the aformentioned winter spinning is 1,755 pounds of wool or 7 tons of wool..... all I can say is...Damn, that's a ton of spinning to finish over a full winter. (It takes me a long while to finish a sweater's worth of wool!)