The distortion of iron crystals

In recent years several attempts have been made to determine what happens to iron crystals when they are strained and various conflicting statements have been made as to the connection between the crystal axes and the nature of the strain. No reliable results have been obtained, however, partly because the largest crystals available were too small tor accurate experiment, partly because workers have assumed that planes of slip coincide with crystal planes—an assumption which the experiments to he described prove to be erroneous— but chiefly because the analysis of strain has not been carried out in a systematic manner so as to obtain all information possible from external measurement of strained crystals. The work of Prof. Edwards and Mr. Pfeil has now enabled us to obtain crystals sufficiently large for the purpose, and, in fact, all the material used in the experiments now to be described was cut from specimens very kindly supplied by them.