Mr. J.M. Kirk read a paper on “The Microscope, its history & use.”

The early history of the microscope & its development up to the present time were described at considerable length, illustrations being furnished by a large collection of Instruments of different dates including examples resembling those used by Leeuwenhoek & Lieberkuhn.

All Microscopes, whether simple or compound, magnify be means of lenses which alter the course of the rays of light passing through them. This principle, which is termed refraction, was rendered intelligible by means of drawings of the various forms of lenses & explanations of their properties. Spherical & chromatic aberration are the principle difficulties to be surmounted in the construction of the objectives used in compound microscopes & these are rendered especially difficult from the small, almost minute size of the glasses worked.

They are “corrected” by using a combination of lenses differing in density & curvature & so arranged that their opposite aberrations shall neutralize each other.

It is only within comparatively recent times that the construction of achromatic object glasses for microscopes has been found practicable – the first attempt in that direction being made in 1823. Amici in 1827 produced a fair achromatic combination but his glasses were soon rivalled by those of Andrew Ross & Powell.

High Power objectives have to be worked very near the object, which is often very inconvenient, this has led to the construction of what are called immersion lenses, the principle of which was carefully explained.