Ah, the ancient and respected trade of the armorer (now called metal worker) the more things change, the more they stay the same.
These men were specialists who were paid an additional rate like teamsters. In winter camps and during lulls in active campaigning they broke out their tools from the battery wagon and forge and went to work. The artificer was primarily a blacksmith - he repaired the wood and iron parts of the battery carriages. The farriers specific task was to keep all the horses and mules shod - a large task considering the number of animals in a battery. There is some evidence that a few batteries had an artificer assigned to each platoon. However, most records indicate that only two men, or a maximum of three, were assigned this duty in a single battery. They received their instructions from the first sergeant and traveled in the rear of the battery near their tools.