Terraria – How to use a switch to turn a timer on without the timer turning itself off

From the 1.0.5 change log

Mud and ash now have a chance to fall like sand when struck.

Playing with it currently I seem to get a mud slide about 1 in 4 mud blocks dug, as the chance is presumably calculated for all neighbouring blocks the actual chance per block is likely lower

As for mining, make a ceiling out of stone or dirt and dig under it, digging down should be easy, be careful when digging sideways to dig at your farthest reach.

for mud you can also plant jungle/mushrooms in it which seems to prevent the falling chance, this would be quite situational as normally if you are tunnelling through it you will be removing the grass/fungi too

EDIT

from the 1.0.6 changelog

Ash and Mud no longer fall due to gravity.

so ash/mud physics is now of interest only as an historic note (unless it comes back again)

The behaviour of the Eater of Worlds has been changed in the 1.0.5 version of Terraria.

I cannot find an explicit reference to the behaviour change in the changelog, but the following line could be interpreted that way:

Changed the way worm enemies spawn.

The wikis don't seem to have been updated yet, but I have observed that you can no longer fight the Eater of Worlds in any biome other than Corruption. If you move away from a corrupted area during the fight, you will see the Eater of Worlds has been slain! message.

If you managed to destroy any of the segments before you received that message, the loot that was dropped will still be there (unless you have saved and exited the game), so you can go back and pick it up. However, if you moved off the corruption without destroying any of the segments, I'm afraid that no loot will have been dropped.

Update:

With the 1.0.6 version of Terraria, you should no longer see this message in this scenario, and should instead be notified that the Eater of Worlds has fled.

From the 1.0.6 Changelog:

NPC Bug Fixes

• EoW is no longer "defeated" when he flees.