Then give her a platinum slab.
Alas, slabs can only be made of rock.
After overcoming numerous issues with the auto version of the cannon, I made it fire two times in a row. Somewhat underwhelming, but still an improvement, since it goes from place to place correctly. I have to adjust the water supply so it can sustain prolonged fire. The bridge dropping the minecart into the reloading system was replaced with a floor grate, which has the same tick delay for activation with a pressure plate, but doesn't make the minecart fly in random directions. I don't know the friction value for grates and floor bars - I assume it's the same as a normal floor tile, not that it matters much. The bad news are that automatisation without using power seems impossible. I had to use rollers. Only about 29 ticks pass between the activation of the pressure plate opening the way for the minecart to return (I had to count that myself in case impulse ramps behave oddly again), so I'd have to keep it somehow "busy" and still moving for circa 70 ticks before sending it back with an impulse ramp, so it doesn't drop back into the reloading system. Maybe somebody else can figure this out, I'm out of ideas. Anyway, I should put up the schematics relatively soon. I hope. Solving one issue breeds another - I even flooded a part of the fort at a time. I'm now more careful about the order in which levers are pulled.
You see, these cannons are going to be a substantial part of the Hell outpost I'm going to construct. This is why I was trying to make a powerless version. I suppose I'll just make an artificial waterfall out of a cavern lake and have it drain into an eerie glowing pit. Of course deep underground nothing stops me from using magma as ammunition, but power must be provided by water. The aboveground part will also see its fortifications lined with cannon batteries.
So the current plans include mining out and processing all the adamantine, constructing an out post in Hell, complete with cannons, silk farms (there are some web-spinning demons I hope to lure into them), a baiting system, marksdwarf bastions and possibly a few more things, building a tall tower out of obsidian, replacing all the furniture with electrum, finishing paving the fort with said metal, creating a new statue garden with mist generators, and couple of other projects I don't remember at the moment.
Speaking of adamantine - the spires go straight through the magma sea, so before I send the miner I have to let in water to obsidianise the surrounding magma. Pockets of magma can even appear
within the spire. I lost a miner this way. I started with the north-western spire - a floodgate, a lever, and a door so the miners can walk in after all is done. Now, the nearby pool is 2 z-levels high. I installed everything, opened the floodgate and sent in a miner to dig out the last tile. I expected him to outrun the water rushing in, but apparently pressure had a different opinion. At one moment, I noticed a job cancellation due to dangerous terrain. The magma was cooled down, but now I had a drowning miner, and it wasn't an ordinary one - he was the creator of Wealthwinters, the second artifact created in the fort's history, the floor hatch which at one moment was the only thing standing between the fort and the demonic Siege From Below, and the husband of late Reg Sneakedurns. While trying to create him an escape route, I noticed he's moving. He approached a nearby ramp and disappeared. This happened a few more times, so I took a look on the z-level above. Now, the cavern pool in question can be divided into two parts - northern and southern, separated by a narrow rock wall cutting it's width to one third of its normal value. The northern part was drained of water so rapidly it became passable, and the miner - after a few attempts stopped by water flow pushing him back - just walked out. Where did the water go?
I shut down the floodgate and left it all for later use. And then a winged ribbon worm Tharumi Murkechoed residing below had the wonderful idea to fly up and wreak some havoc.
In order to even reach it, I had to dig a staircase down to where it was at the moment. Do you remember that Ber Hammerbearded fellow? It ripped out his right arm. And he survived, and even got back to pick up his sword, when the beast was slain. This didn't stop the trouble. The water flooded the entire hallway between the forges, the ore stockpiles and the barracks of the Fenced Neutrality. I hewed out some space above and constructed two pump batteries trying to displace the water, to no avail. It's still there. I guess I'll just make a small pumpstack and add magma to the equation.
There was another beast in the first caverns, with an interesting syndrome. First, unconsciousness. Then numbness and nausea, not that it matters much for an unconscious creature. Then the spine began to rot. Shortly before death, the victim would wake up and spend it's last conscious minutes suffocating and being torn apart by a giant, horned, feathered moose. The artifact trap saved my soldiers.
The dwarven caravan of year 161 did not appear for no apparent reason. Since then, I've received two "The fortress attracted no migrants this season" messages. Something is wrong. Have I driven the home civ extinct?
Some more random fun: