BUTTERFLY WING SCALES 144 CRYSTALS FROM HUMAN BLOOD 168 CRYSTALS FROM THE BLOOD OF THE BABOON 168 CLUSTER CUPS 184 RUST OF WHEAT 184 POLLEN GRAINS ON A GRASS FLOWER 184 LOWER SIDE OF A FERN FROND 184 HEAD OF A BEETLE 200 HEAD OF HERCULES BEETLE 200 A CICADA 200 HEAD OF MANTIS 200 FACE OF A FLY 216 SECTION OF HUMAN SKIN 216 FEELER OF COCKCHAFER 232 VIEW WITH ORDINARY CAMERA 240 VIEW WITH MICRO-TELESCOPE 240 EYE OF A COCKCHAFER 256 HOOKS ON A BEE’S WING 256 SPIDER’S FOOT 264 FLY’S FOOT 264 FLY’S EYE 296 IMAGES SEEN BY A FLY 296 * * * * * The Romance of the Microscope CHAPTER I THE EARLY DAYS OF THE MICROSCOPE It is certain that lenses were used as early as the thirteenth century, and it is probable that they date back to far earlier times. The ancient gem cutters probably used spheres of glass filled with water as magnifiers, their work could hardly have been accomplished without some artificial aid. We know, from early writings, that burning glasses were used by physicians in their work, and Seneca, the author, who wrote in A.D. 63, says: “Letters, however small and dim, are comparatively large and distinct when seen through a glass globe filled with water.” Euclid, whose name at least is familiar to everyone, was, as shown by his writings, perfectly well acquainted with the fact that curved mirrors may be used to magnify objects, and that was so long ago as the third century B.C. Convex glasses, used as spectacles, were first mentioned by Bernard de Gordon, about 1307, but, as far as we know, they were never used for the purpose of studying minute living objects. To Leonardo da Vinci belongs the honour of seriously investigating, for the first time, the properties of concave and convex lenses, and several alchemists, as the early chemists were called, used flasks filled with water, concave mirrors or glass balls to gather together the rays of the sun. “Long before the dawn of the seventeenth century, the principle of the lens was both comprehended and applied to scientific matters by the Englishmen, Leonard Digges and his son Thomas, and by the Italian, Giambattista Porta.”