So working with the concept that period people had it “wrong”, we’d still need to understand their misconceptions. I still don’t have a whole lot in this area, but even so, check this tidbit from Galileo, “Two New Sciences” – translated by Stillman Drake pg. 241-242, based on an earlier edition by Antonio Favaro, (Florence, 1898) “Opere di Galileo Galilei”, volume VIII, pg. 291-292. (You might want to save this one. It’s really interesting)
To that which has been said up to this point about these impetuses, blows, or let us say impacts of projectiles, we should add one other very necessary consideration. This is that it is not sufficient to have in mind just the speed of the projectile, in order to determine fully the force and energy of its impact, but it is further necessary to specify seperately the state and condition of that which receives the impact, in the effectiveness of which this [condition] has a great share and contribution in several respects. First, everyone understands that the thing struck suffers violence thereby from the speed of the thing striking [only] to the extent that it opposes this and entirely or partly restrains [frena] its motion. For if a blow arrives on that which yields to the speed of the striker without any resistance at all, there will be no blow. And he who runs to strike an enemy with his lance, if it happens that as he overtakes him the enemy moves in flight with like speed, will effect no blow, and the action will be a simple touching without wounding. If an impact is received in an object that does not yield to the striker entirely, but only partly, the impact will [do] damage, not with all its impetus, but only with the excess speed of the striker over the speed of retirement and yielding of the thing struck. For example, if the striker arrives with ten degrees of speed upon the thing struck, which, by yielding partly, retires with fource degrees, then the impetus and impact will be as of six degrees. And finally, the impact on the part of the striker will be entire and maximal when the struck does not yield at all, but entirely opposes itself and stops all the motion of the striker, if indeed this can happen.
I said [impact] “on the part of the striker,” because if the struck moves with contrary motion against the striker, the blow and encounter will be made so much the more strongly, as the two contrary speeds united are greater than that of the striker alone. Moreover, it must also be noticed that to yield more, or less, may derive not only from the quality of the materials, harder or less hard, as of iron, or lead, or wool, etc., but also from the placement of the body that receives the impact. If this placement is such that the motion of the striker comes against it at right angles, the impetus of the impact will be maxima; but if the motion comes obliquely, and gives a slanting blow as we say, the blow will be weaker, and the more so according to the greater obliquity. For any object obliquely situated, though of very solid material, does not remove and stop all the impetus and motion of the striker, which escapes and passes on beyond, continuing (at least in part) to be moved over the surface of the opposed resistent.
Galileo wrote this passage to show that the impact of a cannon ball is maximal when the target surface is perpendicular to the projectile’s trajectory at impact, not necessarily when the target is either vertical or horizontal. But to explain his reasoning he ties it to some impact physics that everyone already understands. His passage indicates that everyone in his day understood the essential concepts of closing velocity and target resistance. He’s also putting actual numbers on these closing velocities, so in the 400 years since his day, we’ve gone backwards in our sophistication and knowledge about sword combat. Now we’re left saying “My blows feel powerful!” This passage also implies that if you want to maximize the strength of your opponent’s blows, use direct opposition. And if they thought that maximizing the closing velocity maximizes the impact, as this passage implies, then they might conclude that they should swing hard and fast.
I also have an almost worthless scrap from a book review in the Philosophical Transactions of the Royal Society 1665-1678, Volume I (1665-1666), pg 301-310 (available at
www.jstore.org, but you may have to go to a library for access). In it there’s a review of a book by Monsieur Isaac Vossins, which mostly concerns the flow of the Nile. Page 306 of the Transactions includes this.
There are besides, in this Book, two other Tracks. In the first, M. Vossins endeavours to maintain the Doctrine, he had deliver’d in his Book De Lumine, and to shew, that the Soul of Animals is nothing but Fire, that there are no invisible Atoms; nor so much as any Pores, even in the Skin of man. Here he treats also of Refractions, and alledges the Examples of several persons, who hae then seen the Sun by the means of Refraction, when really He was under the Horizon.
In the second, He discourses on some points of the Mechanicks; and relates among other things, that the Arrows and battering Rams (Aries) of the Antients did as much execution, as our Muskets and Canons; and then, that the Vehemence of the percussion depends as much upon the Length of the percutient Body, as upon the velocity of the Motion. He adds, that the Length of a Canon ought no to exceed 13 foot, and that a greater length is no onely useless, but hinders also the effect of the Gun, not because the Bullet is thrown out of the Gun, before all the powder is fired (as some believe;) but because the Bullet is then beaten back into the Gun by the Air, re-entring into it with impetuosity, when the flame is extinct.
Remember that back then percussion had just one basic meaning, since it hadn’t been applied to music or medicine, and the percussion cap hadn’t been invented yet. Neither of these passages indicates a hang-up about how an impact works. We’ve got someone here saying that the violence of the impact is not just due to the velocity. It sounds like they thought impact was pretty simple, but found guns a bit more confusing. I take it that we didn’t always think our swords were totally mystifying. I’ll have to think about the soul being made of fire, though.
