Evaluation of Stress in Railway Rails
Rail data frame has 18 rows and 2 columns.
Devore (2000, Example 10.10, p. 427) cites data from an article in Materials Evaluation on ``a study of travel time for a certain type of wave that results from longitudinal stress of rails used for railroad track.''
Pinheiro, J. C. and Bates, D. M. (2000), Mixed-Effects Models in S and S-PLUS, Springer, New York. (Appendix A.26)
Devore, J. L. (2000), Probability and Statistics for Engineering and the Sciences (5th ed), Duxbury, Boston, MA.