Bill (weapon) Bill (weapon) The bill is a polearm weapon used by infantry in medieval Europe. The bill is similar in size, function and appearance to the halberd, differing mainly in the hooked blade form. Other terms for the bill include English bill, bill hook or bill-guisarme. Derived originally from the agricultural billhook, the bill consisted of a hooked chopping blade with several pointed projections mounted on a staff. The end of the cutting blade curves forward to form a hook, which is the bill's distinguishing characteristic. In addition, the blade almost universally had one pronounced spike straight off the top like
Types of volcanic eruptions propels it forward. Phreatomagmatic eruptions are another type of volcanic eruption, driven by the compression of gas within magma, the direct opposite of the process powering magmatic activity. The third eruptive type is the phreatic eruption, which is driven by the superheating of steam via contact with magma; these eruptive types often exhibit no magmatic release, instead causing the granulation of existing rock. Within these wide-defining eruptive types are several subtypes. The weakest are Hawaiian and submarine, then Strombolian, followed by Vulcanian and Surtseyan. The stronger eruptive types are Pelean eruptions, followed by Plinian eruptions; the strongest eruptions are called