Show tubes made blade front from steel rods at a recent meeting of the physical society berlin the president prof du dubois bois reymond gave an account of a which bad been made by siemens at the last meeting of the Aka demie der A steel tube 10 cm longwith loog with perfectly smooth external and internal surfaces and extremely tre mel y uniform bore whose walls are apparently of perfectly equal thickness at all points was wa prepared by the following method patented by manner mann in berschied Bem schied two rollers slightly conical toward their lower ends are made to rotate in the same direction near each other a red hot cylinder c y linder of steel is then brought between these cylinders and is abonce at once seized by the rotating cones and is driven upward but the mass of steel does not emerge at the top as a solid but in the form of the hollow steel tube which siemens laid before the meeting prof neesen gave the following explanation of this striking result owing to the properties of the glowing steel the rotating rollers seize upon only the outer layer of the steel cylinder and force this upward while at the same time the central parts of the cylinder remain behind the result is thus exactly the same as is observed in the process ol 01 making g glass lass tubes out os 0 glass rods |