Why a Long Bombard Carries Farther; Compressing Air
The physics of exploding gunpowder, beside a plan and dome of a centralized church
The sheet's main text is a small treatise on gunnery arguing why a long-barrelled bombard shoots farther than a short one, explaining the confined powder as fire that seeks a void and expands violently into the barrel. A note at the top, beside a conical vessel labelled 'water', observes how air can be packed and compressed and then rarefied. At the center Leonardo has drawn a lobed plan of a centralized church and a small perspective of a domed structure, and columns of untranscribed calculations run down the margins.
On this page
How air can be compressed within itself and then rarefied
Beside a conical vessel marked 'water' Leonardo notes how air can be stowed and pressed together within itself, and in the same way spread out again. The line 'Every motion...' is left unfinished.
Proof why the long bombard shoots farther than the short
The powder packed in the breech is much longer than it is wide; once fire is kindled it cannot reach its end without an interval of time, so the ignited part leaps into the barrel seeking a greater void in which more of it can catch fire. If the barrel is long, more powder ignites in succession and drives out every obstacle with greater force.
The multiplied forces converge on the barrel's free exit
All the parts of the resisting bombard withstand the expanded element and gather the interrupted motions into themselves, so that all of them take their concourse toward the free exit. There, Leonardo argues, a multiplication of diverse forces is produced, able to drive out every obstacle.
Plan and dome of a centralized church
At the center of the sheet is a lobed plan of a centralized building with chapels clustered around a core, and below it a small perspective of a domed structure ringed by lower cupolas. These drawings are not covered by the transcription.