As to your theory of "fluxions," I admit myself to be completely at a loss. You seem to be assuming that a curve is made up of an infinite number of infinitely small lines. Where is your authority for such a statement? You append no bibliography and no references, and I cannot find it in the literature. Apparently, you are attempting to handle _zero_ and _infinity_ as though they were arithmetical entities. Where did you learn such nonsense? My boy, please keep it in mind that four years of undergraduate work does not qualify one as a mathematician. It is merely the first stepping stone on the way. You have a great deal of studying yet to do, a great many books yet to read and absorb--books, I may say, written by men older, wiser, and more learned than yourself. Please don't waste your time with such frivolous nonsense as toying with symbols derived from wine barrels. No good can come out of a wine barrel, my boy. I hope you will soon find yourself in a position to aid me in some of the calculations on conic sections as I outlined them to you in my letter of the 28th December last.[1] I feel that this is important work and will do a great deal to further your career. With all best wishes, Sincerely, Isaac Barrow [Footnote 1: This letter was either lost or returned to Dr. Barrow.--S. H.] * * * * * 5 January 1667 London Dear Mr. Newton: Thank you for your tabulations on the seven-pounder. I must say you were very prompt in your work; there was no need to work over the holidays. Your questions show that you are unacquainted with the difficulties of manufacturing military arms; I am not at all surprised at this, because it takes years of training and practical experience in order to learn how to handle the various problems that come up. It is something that no university or college can teach, nor can it be learned from books; only experience in the field can teach it, and you have had none of that. I can, however, explain our method of approach thus: Each cannon to be tested is fired with several balls--some of iron, some of lead, some of brass, and some which have been hollowed out to make room for a charge of gunpowder in order that they may explode upon reaching the target. With each type of ball, we find the amount of powder required to drive the ball five yards from the muzzle of the piece; this is considered the minimum range. (Naturally, with the testing of hollow, explosive missiles, we do not fill them with gunpowder, but with common earth of equal weight. To do otherwise would endanger the cannoneer.)