In the experiment thus described, something can be found for the infinity of the virtue of percussion as will be shown in due place. Nevertheless, it is worth-while to find out the error in the reasoning. To make it clear, the property of percussion which we presented above must be repeated. We said indeed that the motive force of any body results from the violence or intensive force of this body and from its distribution or expansion throughout all the material mass so that no particle of the body can be found which would be deprived of the same impetus and equal velocity. Therefore, the same motive virtue is diffused everywhere throughout the body mass. If two hammers have the same weight and the same velocity, they will carry out two percussions absolutely equal at a median and perpendicular incidence on the same body. Everybody would agree with that. It is also clear that the sum of the two percussions is the double of one single percussion carried out by one hammer. The two percussions produce a double effect whether distraction, compression or impulsion occurs. It is certain that the energy of percussion is doubled in so far as there are two hammers. If the number of hammers increases and all of them deliver a blow at the same velocity on the same body, the energy of the sum of the percussions is equal to as many times that of one single percussion as there are hammers. It is thus obvious that the delivered blows are multiplied as many times. This is the reason why the heavy beam with which walls are rammed, although slowly impelled, disrupts and destroys marble towers. Such machine is an aggregate of as many hammers each of which strikes the wall together at the same impetus with the battering ram.

This is also why a big ship, although moving slowly, pounds and shoots forth machines which oppose it, and sometimes even breaks rocks whereas a small boat moving at the same velocity carries out a very slight percussion on a machine in its way. Percussive force indeed increases not only in intensity with an increase in velocity but also in expansion when distributed over the huge mass of the striking body.