ABSTRACT
Examination of the microstructure of metals has been practised since it was developed by Professor Henry Sorby at Sheffield in the early 1860s. It is most important that the specimen is washed before passing from one grade of paper to the next, and particularly before transferring to the final polishing cloth. The specimen is then grounded on the '220' grade paper. If the first attempt results in a badly stained or discoloured surface then it means that the much of the total light available is lost, by transmission through the glass when it first strikes the plate, and also by reflection when the returning ray from the specimen strikes the plate again. The specimen is brought into focus by using the coarse adjustment and then the fine adjustments. The limitations of the optical microscope have already been mentioned, but it should be noted that the range of the ordinary electron microscope is too limited.
