The instrument known as the Microscope derives its designation from two Greek words, μικρὸς (_mikros_), _small_, and σκοπέω (_skopeo_), _to see or observe_; and is an optical instrument by means of which objects are so magnified that details invisible or indistinct to the naked eye are clearly seen. Its origin, so far as yet can be traced back, seems to be of a doubtful nature. It is tolerably certain the ancients had little or no conception of the magnifying power of lenses; this may be surmised from their writings. The elder Pliny incidentally states that the physicians of his day cauterised by means of “a globe of crystal.” The learned Greek physician, Galen, however, demonstrates conclusively that in the first and second centuries of our era the use of magnifying lenses was quite unknown either to Greek or Roman. Moreover, the writings of Archimedes, Ptolemy, and other learned men, show that, although they had some idea of the action of refraction at plane surfaces, as of water, yet of the refraction at curved surfaces they had formed no conception. Indeed, they refer quite indiscriminately to the spherical form, or the disc, or the plane surface of the water, but not one of them speaks of the lenticular form, or the curvature of their surfaces. As to the more powerful optical instruments, the telescope and microscope, although it would appear that Alhazen in the 10th or 11th century, Roger Bacon in the 13th, and Fracastoro and Baptist Porta in the 16th, had formed some idea that lenses might be made and combined so that distant objects might be seen clearer, or near ones magnified beyond the power of normal vision; yet we hold with Kepler, that no instrument analogous to our telescope was known before the early part of the 17th century. The combination of lenses associated with the name of Galileo, was, he tells us, of Dutch origin, and of a date anterior to that of his telescope, constructed by him in 1609; and this would appear to be the probable origin of the microscope consisting of a combination of a convex object lens with a concave eye lens.[3] It now appears almost impossible to assign the exact date of the first production of the microscope (as distinguished from the simple magnifying lens), but those who have made a special investigation, agree that it must have been invented between 1590 and 1609, and that either of the three spectacle-makers of Middelburg, Holland, Hans Janssen, his son Zacharias Janssen, and Hans Lippershey, may have been the inventor, the probabilities being in favour of the Janssens, and there the question must remain.