Manufactured in England c.early 19th century. ~.30 caliber ball, patina’d cast steel ball air tank good for half a dozen shots at effective range. I love these old air rifles, they never were extremely popular, at least not in the military, because of the fragility of these early air reservoirs. The Austrian army did use the Girardoni air rifle in the late 18th century, but this raised yet another problem of filling the reservoirs back up after usage which was either really long and labor-intensive or required a specialized cart.
Another air rifle with an offset top-mounted brass air tank.