Briefly list the characteristics of goblins explain how they use the technology they have for evil purposes.

From the text:

"There in the shadows on a large flat stone sat a tremendous goblin with a huge head, and armed goblins were standing round him carrying the axes and the bent swords that they use. Now goblins are cruel, wicked, and bad-hearted. They make no beautiful things, but they make many clever ones. They can tunnel and mine as well as any but the most skilled dwarves, when they take the trouble, though they are usually untidy and dirty. Hammers, axes, swords, daggers, pickaxes, tongs, and also instruments of torture, they make very well, or get other people to make to their design, prisoners and slaves that have to work till they die for want of air and light. It is not unlikely that they invented some of the machines that have since troubled the world, especially the ingenious devices for killing large numbers of people at once, for wheels and engines and explosions always delighted them, and also not working with their own hands more than they could help; but in those days and those wild parts they had not advanced (as it is called) so far. They did not hate dwarves especially, no more than they hated everybody and everything, and particularly the orderly and prosperous; in some parts wicked dwarves had even made alliances with them. But they had a special grudge against Thorin's people, because of the war which you have heard mentioned, but which does not come into this tale; and anyway goblins don't care who they catch, as long as it is done smart and secret, and the prisoners are not able to defend themselves."