While widely quoted as an example of failed predictions about technological progress and attributed to Lardner, there are no known citations of this line prior to 1980 and it does not seem to appear in his published works. It may result from the conflation, through imperfect memory and oral transmission, of reference to three separate concepts: the real, and at the time new, danger of suffocation by engine combustion gasses in tunnels (and in particular an 1861 incident http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=202 in the Blisworth Tunnel), the hypothetical (and unfounded) fear of suffocation by vacuum in a speculated system of trains propelled by pneumatic force https://books.google.com/books?id=2Tc1AQAAMAAJ&lpg=PA261&ots=lL3eBeyoex&dq=lardner%20train%20speed%20suffocation&pg=PA261#v=onepage&q=Lardner&f=false, and Lardner's erroneous prediction of mechanical failure of trains in the Box Tunnel of the Great Western Railway from over-acceleration due to excess gradient.
Misattributed
