▁to ▁a ▁co pper ▁bo iler , ▁termin ating ▁below ▁the ▁water ▁level ▁inside ▁but ▁describing ▁an ▁invert ed ▁U ▁above ▁it ▁in ▁the ▁manner ▁of ▁a ▁sy phon . ▁A ▁fire ▁of ▁char co al ▁would ▁heat ▁the ▁vent ed ▁end ▁of ▁the ▁can non ▁and ▁the ▁bo iler ▁so ▁that ▁the ▁metal ▁of ▁the ▁can non ' s ▁end ▁would ▁became ▁red ▁hot ▁and ▁the ▁bo iler ▁would ▁bo il ▁vig or ously . ▁Ste am ▁would ▁be ▁allowed ▁to ▁escape ▁from ▁the ▁bo iler ▁through ▁an ▁opening ▁with ▁a ▁sc rew ed ▁thread ▁so ▁there ▁would ▁be ▁no ▁bu il dup ▁of ▁pressure . ▁To ▁fire ▁the ▁can non ▁a ▁cap ▁would ▁be ▁sc rew ed ▁tight ly ▁into ▁the ▁bo iler ▁opening , ▁trigger ing ▁an ▁immediate ▁bu il dup ▁of ▁steam ▁pressure ▁in ▁the ▁bo iler . ▁This ▁would ▁force ▁the ▁bo iling ▁water ▁along ▁the ▁sy phon ▁t ube ▁into ▁the ▁can non ' s ▁base . ▁Here ▁it ▁would ▁come ▁in ▁contact ▁with ▁the ▁red ▁hot ▁can non ▁walls ▁and ▁flash ▁into ▁steam , ▁the ▁pressure ▁of ▁the ▁sudden ▁release ▁of ▁steam ▁forcing ▁the ▁can non ball ▁out ▁of ▁the ▁m uzz le . ▁ ▁Leon ardo ' s ▁own ▁description ▁Account ▁from ▁the ▁Nelson ▁Ex am iner ▁and ▁New ▁Zealand ▁Chron icle , ▁ 1 8 4 2 : ▁ ▁The ▁Ste am - Engine . ▁– ▁M . ▁De le cl u ze ▁has ▁l ately ▁made ▁a ▁discovery ▁among ▁the ▁manuscript s ▁of