Comparing Embrasures: Wide Mouth versus Wide Within
Cross-sections weighing each gun-loop's strength and the defender's safety
A band of three hatched cross-sections across the middle of the sheet shows splayed embrasures, with balls and lettered points marking where the artillery strikes. The opening line states a rule of impact: every reflected motion loses the more power the closer the line it springs from lies to the line of incidence, and the reverse. Below, Leonardo asks what difference there is between embrasures wide at the mouth and those wide within, taking a b as the outer part. He proposes to split the inquiry in two, first demonstrating each embrasure's own strength in receiving the artillery's blow, then the comfort and safety it gives the defender.
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A reflected motion is weakest near the line of incidence
Every reflected motion loses the more power, the closer the line from which it springs lies to the line of incidence, and conversely gains as that line diverges. This principle governs how a shot rebounds within the splayed throat of an embrasure.
Two questions on embrasure design: strength and the defender's safety
Leonardo asks what difference lies between embrasures wide at the mouth and those wide within, taking a b as the outer part and lettering the sections b f o a - p - o n - c m q d. He divides the study in two: first the intrinsic strength of each embrasure in receiving the artillery's impact, then the comfort and safety it affords its defender.