On weights.

* Many small weighty bodies joined together and united will have a greater weight than when separated. That is, if you take lead filings or ground glass, and weigh them and then melt them together, you will find that they have increased.1

On blows.

* If you let a one-pound hammer fall one hundred times from the height of one braccio2 onto a lead bar, and then take a hammer or another weight having the same thickness as the hammer and of such a length that it weighs one hundred pounds, and make it fall that same height of one braccio onto a lead bar like the first one, you will see how much more the bar of the united blow3 penetrates than the first.

On flight.

* Flight goes contrary4 to this, for if5 a one-pound crossbow shoots an arrow6 one hundred braccia, a ten-pound crossbow does not thus shoot its arrow a thousand braccia;7 and this is the same for all instruments using violent motion to generate a second movement, made by the thing thrust and shot8 from the instrument.

On flight.

* A stone or another weighty thing cast with violence will change its line of course at the middle of its path.  And if you know your crossbow will shoot two hundred9 braccia, position yourself one hundred braccia from a bell tower and aim over the bell tower and shoot your arrow, and you will see that, at one hundred braccia beyond the bell tower, the arrow is driven in perpendicularly.  And if you find this to be so, this is a sign that it had finished its violent motion and had entered into natural motion, meaning that, being a weighty object, it was falling freely toward the center [of the earth].

On the arrow shot by the crossbow.

* If a crossbow or another machine hurls a four-ounce10 weight four hundred braccia, then if four weights of one ounce each were given to it, these would not reach the first four hundred braccia.

On the blow.

* If a hammer falls four braccia onto a lead bar and penetrates into it the depth of one finger, a hammer falling11 eight braccia will penetrate the depth of one and one-half fingers.

On weight.

* If a four-pound hammer falling from a height of three braccia penetrates the depth of one finger into lead, a hammer of the same thickness and double the weight, falling from the same height as the first one, will not penetrate the lead twice12 as deep as the first, but rather one and one-half times.