Defining "Mechanical"

When the Congress put a provision prohibiting "mechanical transport" in Wilderness areas, in the 1964 Wilderness Act, what did they mean?

Our best guess is that they meant motorized vehicles and equipment. But to aid discussion, we provide here the definitions of "mechanical," "machine" and "vehicle," From the 1964 edition of Webster's New Collegiate Dictionary.

me-chan-i-cal, adj. 1. having to do with machinery or tools. 2. produced or operated by machinery or a mechanism. 3. of, in accordance with, or using the principles and terminology of, the science of mechanics. 4. machinelike; automatic, as if from force of habit; lacking spontaneity, expression,intelligence, etc.: as, her acting is mechanical. 5.[Archaic] a) of manual labor. b) of manual laborers; of the artisan class c)base or vulgar.

ma-chine, n. 1. [Rare or Archaic], a structure or built-up fabric of any kind; specifically, the human or animal frame. 2. a) a vehicle, as formerly, a carriage, cart, etc. b) a vehicle operated mechanically; specifically, an automobile. 3. a structure consisting of a framework and various fixed and moving parts, for doing some kind of work; mechanism; as a seeing machine. (4.-7. not relevant) 8. in mechanics, a device that transmits, or changes the application of energy: the lever,wheel, and screw are called simple machines.

ve-hi-cle, n. 1. any device on wheels or runners for conveying persons or objects, as a cart, sled, automobile, etc. 2. any means of carrying, conveying, or communicating. (3. - . not relevant)