under bed spring--which in the mid-1800s was also called a mattress or base layer of a bed. Crofton's work of 1834 and Felton's work of 1793, in light of archeological finds and great works such as Sir Robert Hooke's Lecture on Springs, clearly indicate that coil springs came into use in the 17th or 18th century. The time, location, and inventors are unknown. See also Mattress coil Box spring References Furniture-making Springs (mechanical)