3 i e the improved cylinder insures a maximum density flow of heat energy between the composite shell 11 12 and the paper web fig2 further shows the advantage of the hood 6 which insures that the major part of heat transfer between the cylinder and the web takes place in the region including the first half of the path of the web from the location b to the location c the thickness of the layer 12 is preferably a minute fraction of the thickness of the shell 11 most preferably in the range of 0 4 2 millimeters the heat expansion coefficient of the material of the layer 12 preferably equals or at least approximates the heat expansion coefficient of the material of the shell 11 for example the layer 12 can be applied to the shell 11 by resorting to a flame spray coating technique copper is but one of the materials which can be used as a coating or layer at the periphery of the shell 11 it is important to select a material whose heat conductivity is pronouncedly higher than preferably at least two times that of the shell 11 in addition to copper such materials include molybdenum tungsten their alloys and certain other metals as a rule the shell.