Various Questions and Inventions

S.D. I concede this to you, that is, that by firing either directly upward toward the sky, or directly downward toward the center of the world, the transit, or motion, of such a ball is entirely straight. And I also concede to you that in these two directions such a ball travels much more in a straight line than in any other elevation or in any other direction. But that in any other direction besides the aforementioned two, it does not travel any part of its motion straight, that is, in a straight line, that does not seem to me a thing to be believed, nor do I believe it. Because if you remember well what you said above, that for those two shots fired at Verona, you found that the said culverin original: "colobrina" of 20 lbs fired by sight, that is, by a straight line as far as the senses are concerned, for about 200 paces while leveled. Now, if you then found with reason that such a transit of 200 paces is not totally straight, that is, not totally by a straight line, I believe you, and I concede it to you. But if such a piece cannot fire the said 200 paces in a straight line, do you not wish to concede that such a machine would fire at least half of it, that is, 100 paces? And if not 100, at least 50?
N. Not only will it not fire those 50 paces in a perfectly straight line, but it will not fire even one single pace.
S.D. Your talk is madness.
N. Reason is what quiets the intellect of men, for it discerns the true from the false.
S.D. It is the truth.
N. Since it is your Excellency’s opinion that the ball fired from such a leveled culverin must go a part of its transit, or violent motion, in a straight line, and the rest then in a curved line, given that this were the truth, I would like to know from you what is the specific cause that such a ball travels thus in a straight line in the part where you suppose it travels so straightly, and what is likewise the cause that it travels thus in a curved line in the part where your Excellency supposes it travels so curvedly.
S.D. The very great velocity found in the motion of such a ball, upon exiting the mouth of the piece, is the very cause that for a little time, or space, such a ball travels straightly through the air. But afterward, as the vigor and velocity in it diminish, it begins then to slacken and to lower itself successively toward the earth, and thus it continues until it strikes upon it.
N. Certainly your Excellency could not have answered better than you have answered, that is to say, that the great velocity is the very cause of reducing the motion of such a ball (if it is possible) to straightness, and similarly, the lack of velocity in it is the very cause of making it tend and decline in its motion curvedly toward the earth. And the more the said velocity continues to diminish in it, the greater it makes its declination, or curvature. And all this proceeds because any heavy body corpo graue heavy body pushed violently through the air, the faster it goes, the less heavy it becomes in such motion, and therefore it goes more straightly through the air, because the air supports a body more easily the lighter it is. Yet in performing its effects in such motion, it assumes much greater gravity than its own, and therefore the faster a heavy body goes (in violent motion), the greater effect it makes on any resistor. Similarly, the more the velocity in it goes missing, the more its gravity grows in such motion, which gravity is continually stimulating it and pulling it toward the earth. But in performing its effects in such motion, it assumes greater lightness, or less gravity, and therefore it makes less effect.
S.D. This discourse of yours does not displease me, so continue.
N. I say then that from these things said, and approved by natural reason, is born this...