A water block becomes a source block when there's at least 2 other source blocks next to it (not counting diagonally). You start with the very edge and place two water blocks like so. This will give you a 2×2 square of water sources.
__________
|Wo |
|oW |
| |
| |
| |
W = water source placed by you
o = water source generated by the water mechanics
Now, simply scoop up any source block (it will refill), and dump it diagonally from the outermost block.
__________
|Woo |
|oWo |
|ooW |
| |
| |
Repeat until you hit an edge. Which source block you take doesn't matter, they are all infinite (as in, will refill instantly) at this point.
__________
|Woooo |
|oWooo |
|ooWoo |
|oooWo |
|ooooW |
As you can see, to fill an n-long square, you need n bucket loads (actually, only 2, since after that, you can refill from the pool).
To fill the entire rectangle, dump a bucket every other row on one side. The very edge block always has to be filled.
__________
|Wooooooo|
|oWoooooo|
|ooWooooo|
|oooWoooo|
|ooooWWoW|
So to fill an n×m block rectangle, you need n + ceil((m - n) / 2)
water sources, with m being the longer side. Again, only 2 if you're talking resources, because after that, you're drawing from an infinite pool.
Here's a video of a guy using this technique on a square:
(Note that he always refills from the still source blocks for some reason, but as noted above, any source block will do.)
I made a pretty quick and dirty XP farm as such:
Find a zombie spawner, punch out all the blocks around it, leave 3ish blocks of space all around it, making a big dark room around the spawner.
Put water source(s) at one end of the room, pulling every zombie that drops to the other side of the room. Make a 1-wide hallway for the water to flow into. Where the water stream ends, put in a 1x1 vertical shaft for the zombie to drop down (place this RIGHT AFTER the water, don't let water flow down the hole).
Make the bottom of the "tube" out of glass so you can see the zombies inside the "kill zone". Leave a single block at the bottom so that you can swing your sword at the zombie's feet.
I made my vertical shaft high enough to take away ALMOST all the zombie's health. If the fall kills them, no XP bubbles. I got mine to the perfect height that I can 1-shot all the zombies with a stone sword (you wouldn't believe how fast this goes through swords).
Hope my description isn't gibberish, I'll get some screenshots later if this isn't clear. =)
|
|
S <-zombie spawner |
|
|
WWWWWWWWWWWWWWWWWWWWWWWWW |
| | <- vertical shaft - experiment with height
| |
G G <- glass
G G
<- air for swinging sword
xxxxxxxx <- floor
Best Answer
Mining
Branch mining is the most efficient. There's a mathematical analysis on it in the official forums (the link is to an archive of the post).
Here's a brief description of branch mining:
So essentially, a long hallway (the trunk) with perpendicular hallways (the branches) coming off either side.
From a head on view
Travel
As with any mine, travel is most easily accomplished using minecarts.
You can place a booster to get your cart traveling at max speed in a short distance so that you can make the trip up quickly, and you can even attach chests to mine carts to carry all your findings from the mine up the track very quickly.
Short of minecarts, make sure you're using stairs and ladders to their fullest potential. You don't want to be jumping up one block at a time all the way from your mine to your base.