In railroading, a flying switch is made by uncoupling the cars from the engine while in motion, and throwing the cars onto the side track, by turning the switch, after the engine has passed it upon the main track. Greenleaf v. Illinois Cent. R Co., 29 Iowa, 39, 4 Am. Rep. 181; Baker v. Railroad Co., 122 Mo. 533, 28 8. W. 20.