15.6 **Tons** 15.2 **Tons** **steam-engine**, **representing** **graphically** **by** **a** **curve** **CPD** **the** **relation** **between** **the** **volume** **and** **pressure** **of** **the** **powder-gas**; **and** **in** **addition** **the** **curves** **AQE** **of** **energy** **e**, **AvV** **of** **velocity** **v**, **and** **AtT** **of** **time** **t** **can** **be** **plotted** **or** **derived**, **the** **velocity** **and** **energy** **at** **the** **muzzle** **B** **being** **denoted** **by** **V** **and** **E**.

3 **parallel** **to** **AM**; **the** **energycurve** **AQE** **would** **be** **another** **straight** **line** **through** **A**; **the** **velocitycurve** **AvV**, **of** **which** **the** **ordinate** **v** **is** **as** **the** **square** **root** **of** **the** **energy**, **would** **be** **a** **parabola**; **and** **the** **acceleration** **of** **the** **shot** **being** **constant**, **the** **time-curve** **AtT** **will** **also** **be** **a** **similar** **parabola**.