Suggestions on how to build your own Monkey and Hunter demonstration.

If you do not know about the Monkey and Hunter demonstration, you must find an experienced physics teacher and have her/him describe it to you. It is one of the most outstanding demonstrations in all of physics. Building a Monkey and Hunter demonstration is a right of passage for all physics teachers. Your school may have one in the stock room built by the previous teacher but, it won't work, trust me!. You must fool with it, learn its special needs and when you finally can make it work, you will have arrived!! There are wimps out there who buy the apparatus from a scientific supply house but they probably aren't high school teachers since the price they demand is far beyond the amount any real high school could afford. Use the money they want for this demonstration to buy spring balances (calibrated in newtons) meter sticks, or other much more useful equipment.

1. First locate a few steel balls about 1/2" in diameter and go to a hardware store or building supply warehouse and find a metal tube that will allow the ball to slip through the tube easily. The tube should be about a meter long and they usually sell this stuff in 3 ft lengths. Remember, this will be the "blow gun" you will use to fire the ball across your room. The ball must fit, not too tight and not too loose and I can't even say if the ID of the tube should "match" the OD of the ball. You just have to search to find the perfect match.

2. Over the years, you will improve your "Monkey", perhaps you students will help you with this. For now, any object about the size of a football will work and it must be ferromagnetic or least have a large chunk of ferromagnetic material on its "top". A 2 pound coffee can (empty!!) will work.

3. Locate or wind a small coil of wire around a ferromagnetic core which when energized with about one or two amps of current, will supply enough magnetic force to hold up the "monkey". Make sure the core of this electromagnet as well as the ferromagnetic part of the monkey is "soft iron" or some such so that it will NOT become permanently magnetized when the current is discontinued.

4. The basic idea, of course, is to make a complete circuit with the magnet mounted high at one end of the room and the "gun" located at the other end of the room and some sort of device on the gun which will break the circuit when the "bullet" passes by the end of the gun barrel. I have failed with many elaborate methods of accomplishing this simple technical feet and here is the easiest and best I have come up with:

5. Be sure to CLAMP the gun onto a firm table at one end of the room. Without the bullet in the barrel, complete the circuit exactly as will be done when the monkey is to be shot, hang the monkey on the electromagnet at the other end of the room and adjust the gun by looking down the barrel until it points at the center of the monkey. Firmly clamp the gun in place. Break the circuit and the monkey will fall. (If it doesn't, you still have some work to do!!)

6. Load the gun, place the trigger in place to complete the circuit, hang the monkey and the rest is obvious. Experiment with blowing hard, soft, etc. The only thing you must do is to be sure the ball hits the monkey before it hits the floor. If you do the experiment several periods in a row, make sure the gun has not been bumped between periods--that is, check alignment before each run.

7. Enjoy--you have arrived!!