Jess (falconry) chase something it shouldn't, and less to keep the bird from getting away, as falconry birds are routinely (and as part of the sport) set free—the bond between bird and falconer serves as a much better leash than any leather or rope ever will; however, it is not always desirable that a bird be able to take flight at its own whim, and both on the glove and on the perch, jesses help ensure this. During hunting season (small game season for North American falconers), jesses are generally worn all season in the mews, and are often removed for the
Leather cannon especially if the terrain was uneven. Gustavus Adolphus' tactics were based on use of effective firepower. While heavy cannon were effective at the start of the battle, they could not be moved from the hill that they usually were deployed on (the guns themselves weighed from roughly 300 kilograms (660 pounds) to 3 tons). As such, the artillery could not respond effectively to developments in battle. In order to fill the gap, the so-called "leather cannon" was developed. A relatively thin copper tube was reinforced by heavy cords and finally clad in leather (alternatively clad in leather straps first and