Show RAILS AND WEATHER track tracks grow long or ph art aa a it Is I 1 hot or r cold A t contributes to the hallway railway age some data regarding the expansion and contraction of etcel steel raili under variations of temperature tempera tur which suggest some interesting calculations stool steel rails contract or expand ono part pail in each parts with each degroo degree of change in temperature the pennsylvania railroad tracks from philadelphia to pittsburg Pitta burg are am miles in length and in this distance tho the expansion or contraction would amount to about foot tor for each degree of change in temperature bap tween tia ninety degree degroo weather ol 01 august and the zero temperature of mid fintor the tracks shrink 1134 feet or more than one ono fifth of a mile if tho the tracks vere were continuous rails mils without joints and anchored immovably at tho the pittsburg end the philadelphia end would shrink fron from fifteenth street out to seventh street by christmas time and would not return until july or if the ends of the rails wore were at fifteenth street in the winter they would push through the front walls of the station and upset the equestrian figure of general reynolds in front of the public buildings by tha the time of hot weather rails ore am laid however with a sufficient clent distance between each length to permit contraction and expansion without distort distortion on of the laae or truck track and the space between each lath mu is determined by the temperature at the timo time the rails ore are laid wd |