A Numbered-Grid Locator Slide for Relocating Microscopic Fields

Four strips of drawing paper, each 22 × 30 cm, are taken. Numbers are typed from a typewriter with elite type face in such a way that, when pasted side by side along their lengths on another sheet of drawing paper, they yield a 88 × 30 cm master copy carrying numbers commencing from 1001 at top left and ending with 6680 at bottom right, each number preceded and succeeded by a dot. The upper and lower edges of this rectangle containing these figures are then extended by lines 2 cm each to the left and the ends jointed to make up a 90 × 30 cm master copy from which a 3 × 1 inch (7.5 × 2.5 cm) slide is prepared by photographic reduction. To use this slide, the microscopic field is found, the slide carrying the tissue is exactly replaced by the locator slide, and the number recorded. For subsequent reference, the procedure is reversed by first finding the number and then replacing the locator slide by the one bearing the tissue