Photo -- See Caption Below

Trundle Toy

Lincoln liked to study various topics, including engineering.  Legend says that this was an early version of an invention involving a cart with solid axles (the forerunner of independent suspension used on cars today), or it may have been cart for his sons to play with. 

Wood, paper. H 4, W 16, D 9.5 cm
Lincoln Home National Historic Site, LIHO 6762