The catapult at left is the product of a "What if ?" that I asked myself after reading the Dover reprint of  The Crossbow.  What I asked was, "How far could one of these throw a golf ball if made from modern (early 60's) materials ?"  To spare you the suspense, the answer is "Far enough to find very few places where it can be fired safely."  In other words, about 250 yards, nearly noiselessly (thanks to the piece of rubber vacuum hose hiding behind the felt cover in the center of the crossbeam).  Not only 250 yards out, 250 yards up.  The four-fold ruler used for scale is two feet long; and the catapult weighs about ten pounds.

Was it accurate ?  Nope; a knuckleball effect combined with the wind, I guess.  The sling (instead of the traditional plain, cupped arm) adds about 50 percent to the range, but must be carefully tuned.  If you don't cock the arm fully (full cock requires that the catapult be raised up off the ground a bit in order that the projectile does not start from a position lying on the ground) then the ball shoots straight up, which can be a little frightening if you lose it in the sun.

 The catch is made from three pieces of solid tool steel (left in the annealed condition) by vigorous use of a jeweler's saw.  One has to be exceedingly aware of the catapult's power, as it would not do your head a bit of good to get in the way of the arm or ball if watching the release action of this catch too closely.

 The skein consists of several hanks of nylon mason's twine, which has the important features of extreme strength (250 pounds) and stabilization. The latter term means that the nylon has been stretched to remove its property of cold drawing, wherein it deforms by the discontinuous formation of local necks which form under tension and then propagate lengthwise along the fiber until all of it has been stretched several times over in length.  The stabilized nylon holds its tension under prolonged loading (as while laying brick, lest we forget for whom it was made); the particular skein you see here has been under high tension for more than thirty years.  The installation of the skein is almost as tedious as doing one's taxes; it all has to fit through the small gaps between the crossbars and the ID of the main gear.  There is no quick way of doing that.

The gears are straight out of the Boston Gear catalog, plus a little machining.  The main gear is lubricated by a Teflon backup pad, while the pinion rides in an oil-filled porous bronze bearing.  The tension in the skein is limited mainly by my nerve in applying torque to the slender (1/2 inch) hex that is integral with the pinion.

The mechanical advantage of the winch mechanism seen in the first picture is so great that the catapult can be fully cocked by a small child, which was naturally done under strict adult supervision.

The wood is maple, except for the arm, which was made from green hickory.