For ground propulsion the first instrument was the wheel.
For water propulsion pole, paddle, oar and sail have been used. Nowadays the most common types are underwater propellers. Sails are still common, and historically represented the most important form of early propulsion for large ships.
- A Dictionary of Aviation, David W. Wragg. ISBN 10: 0850451639 / ISBN 13: 9780850451634, 1st Edition Published by Osprey, 1973 / Published by Frederick Fell, Inc., NY, 1974 (1st American Edition.), Page 216.