The science of percussion: hammer, anvil and the blow

The four things to consider in percussion

In percussion one must consider four things: the power that moves the striker, the nature of the striker itself, the nature of the thing struck, and of the thing that supports the body being struck.

The blow harms most where nearest the strike

The hammer breaks a stone held in the hand and the sickle cuts twigs held in the hand: a sign that the blow most offends the part of the struck body nearest to the place of percussion. The same is restated at the centre of the sheet.

Speed of the striker and instantaneous impact

Whatever proportion a b has to c d, such has the power of percussion greater above than below. The swifter the motion, the more powerful the blow; and the act of percussion is made in an indivisible time, on the surface of the struck body at the end of its line of motion.

Cutting the air before it can flee

The whole line of motion b c is made in the time of line n m, itself made in almost indivisible time; so the thing cut in the air has no time to flee while the knife (a n m) passes through the body.

Hammer and anvil width shapes the worked iron

If the anvil is wider than the hammer, the struck iron lifts its ends; if the hammer is wider, the ends turn down. Striking one end twists the iron like a screw, striking the middle hollows it like a roof-tile.

Ring driven up a rod by the blow

A ring threaded on a rod struck by a hammer rises against the place of percussion, one of several small tool figures probing how impact transmits along a body.

Nel margine superiore:

A destra, dall'alto in basso:

Figura colle lettere:

Figura con i numeri e le lettere:

Entro la figura di un cerchio:

Accanto a un altro cerchio:

In alto al centro:

Sotto la figura di un martello e un oggetto ricurvo:

Figura colle lettere:

Figura colle lettere:

Figura di martello che percuote un coltello retto da una mano mentre taglia una pesca 3), senza scritto. Figura colle lettere:

Figura di anello infilato su un asta percossa da un martello:

In basso, figura di incudine su cui poggia un ferro ricurvo battuto da un martello:

Con riferimento ad analogo disegno posto più in alto:

In basso, sotto le figure di martelli:

Sul lato sinistro dall'alto in basso:

Figura colle lettere:

Figura di quadretto:

Quattro schizzi: due linee ondulate, una linea a zig zag, due rettangoli uno dei quali con diagonale e l'altro colle lettere:

Figura di due barre di ferro di varia sezione colle lettere:

In basso tre figure di ferri battuti, diritto e ricurvi. A sinistra in basso:

In the upper margin:

Right, from top to bottom:

Figure with letters:

Figure with numbers and letters:

Within a circle figure:

Beside another circle:

At the top centre:

Under the figure of a hammer and a curved object:

Figure with letters:

Figure with letters:

Figure of a hammer striking a knife held by a hand cutting a peach, without text. Figure with letters:

Figure of a ring threaded on a rod struck by a hammer:

Below, figure of an anvil on which a curved iron rests, beaten by a hammer:

With reference to a similar drawing placed higher up:

Below, beneath the figures of hammers:

On the left side, from top to bottom:

Figure with letters:

Figure of a small square plate:

Four sketches: two wavy lines, a zig-zag line, two rectangles one with a diagonal and the other with letters:

Figure of two iron bars of varying section with letters:

Below, three figures of beaten irons, straight and curved. Lower left:

On this page

The four things to consider in percussion

The blow harms most where nearest the strike

Speed of the striker and instantaneous impact

Cutting the air before it can flee

Hammer and anvil width shapes the worked iron

Ring driven up a rod by the blow