480 Transactions of the AirsRiCAN Institute. 



time overcome the inertia of your knife and pitman, weighing from 

 twelve to fifteen pounds, i. e., stop its motion at each four inches 

 and start it again. Uncle Joe, I don't believe you've got five 

 pounds of force in that knife more than you need to cut upland 

 grass. In fact, I doubt if your whole force would move a twenty 

 jDouud weight against the knife. So you see I am in favor of heavy 

 machines, or else a machine with a weight on it, like yourself or 

 your equivalent in pot metal or stones. Because the velocity 

 being limited to that of a walking horse, we have no way to 

 increase the momentum but by increasing the -weight. Again, you 

 see, I want the knife and pitman and their connections as light as 

 possible. And again, I want the drivers to have a wide rim and a 

 large diameter, because it gives more surface for traction, brings to 

 the ground more callvs to hold on and keep that point still, while 

 the rest of the wheel moves around it as the axis of motion; and 

 because a large wheel mounts obstructions easier than a small one. 

 Then I want the shafts well fitted to the boxes on short bearings; 

 the cogs narrow and perfectly matched, because small surfaces have 

 less friction than large ones; and in regard to the finger bar, I 

 •want it carried by a lifting connection with the main frame, and not 

 by a pushing connection; because the one elevates it over lumps, 

 stones and hillocks, and at the same time gives the weight lifted to 

 the drivers for power, w^hile the other presses the bar against the 

 ground and into the hillocks, and lifts just so much w^eight off the 

 drivers and wastes it." 



" Yes; I see; but I have got a truck wheel to carry the bar and 

 make it run easy." 



"Yes, of course you have, but all you can say in favor of that is 

 that it keeps you from ' running the thing into the ground ! ■ Tlie 

 tendency is just the same — the force is in the same direction. I 

 admit that the little wheel makes a bar in such a position carry 

 easier, for I am not sure it would go at all without it, but I have 

 an objection to it anywhere. You see the knife has motion in two 

 directions: One drives it right and left, the other carries it for- 

 ward; and so the knife, acting in obedience to nature's law, moves 

 in a direction between the two — a diagonal direction. Now, your 

 little w^heel jjives it an irregular motion in another direction, viz: 

 up and down. This is the very w^orst direction you could give it, 

 because it prevents a regular or smooth cut, and makes a notched 

 stul)ble. On a perfectly level surface, of course, this evil would 

 not occur. 



