Solve these clues to fill the grid.
- An aircraft without wings that obtains its lift from the rotation of overhead blades
- 4 Across
- A wheeled vehicle with large wheels
- 7 Across
- A line or route along which something travels or moves
- 9 Across
- Common Old World thrush noted for its song
- 10 Across
- A wheeled vehicle consisting of a self-propelled ___ that is used to draw trains along railway
- 11 Across
- A depository for collecting and displaying objects having scientific or historical or artistic value
- 12 Across
- United States clockmaker who introduced mass production
- 1 Down
- United States writer whose novels explored human alienation
- 2 Down
- A railroad employee in charge of ___ and point in a railroad yard
- 3 Down
- Line that is the commercial organization responsible for operating a system of transportation
- 5 Down
- A facility equipped with special equipment and personnel for a particular purpose
- 6 Down
- Dramatist of ancient Rome whose comedies were based on works by Menander
- 8 Down