The Romans, working constantly with their rams, continued to break down portions of the wall,
but they were not able to force their way in through the breach, as the defenders worked hard at counter-walling, and fought gallantly on the ruins.
So, as a last resource, they took to mining and digging underground.
Having secured the middle one of the three machines they previously had on this site and covered it carefully with wattle screens, they constructed in front of it a covered gallery running parallel to the wall for about a hundred yards,
from which they dug continuously by day and night, employing relays.
For a good many days they carried out the earth by the underground passage without being noticed by the defenders, but when the heap of earth became considerable and visible to those in the city, the leaders of the besieged set vigorously to work to dig a trench inside the wall parallel to the wall itself and to the gallery in front of the towers.
When it was sufficiently deep, they lined the side of the trench next the wall with exceedingly thin plates of brass, and advancing along the trench with their ears close to these, listened for the noise made the miners outside.
When they had noted the spot indicated by the reverberation of some of the brass plates, they began to dig from within another underground passage at right angles to the trench and passing under the wall, their object being to encounter the enemy.
This they soon succeeded in doing, as the Roman miners had not only reached the wall but had underpinned a considerable part of it on both sides of their gallery of approach.
On meeting, they first of all fought underground with their pikes, but when they found that they could not effect much by this, as on both sides they used bucklers and wattles to protect themselves,
some one suggested to the besieged to put in front of them a large corn-jar exactly broad enough to fit into the trench. They were to bore a hole in the bottom of it, and insert into this an iron tube as long as the jar: next they were to fill the whole jar with fine feathers and place quite a few pieces of burning charcoal round its extreme edge:
they were now to fit on the mouth of the jar an iron lid full of holes and introduce the whole carefully into the mine with its mouth turned towards the enemy.
When they reached the latter they were to stop up completely the space round the rim of the jar, leaving two holes, one on either side, through which they could push their pikes and prevent the enemy from approaching it.
They were then to take a blacksmith's bellows and fitting it into the iron tube blow hard on the lighted charcoal that was near the mouth of the vessel among the feathers, gradually, as the feathers caught fire, withdrawing the tube.
Up all those instructions being followed, a quantity of smoke, especially pungent owing to its being produced by feathers, was all carried up the enemy's mine, so that the Romans suffered much and were in an evil case, as they could neither prevent nor support the smoke in their diggings.
While the siege thus continued to be prolonged, the strategus of the Aetolians decided to send envoys to the Roman consul.
Walbank Commentary