Fifth Meeting: 29th August, 1910.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 43, 1910, Page 38

Fifth Meeting: 29th August, 1910. Dr. R. Briffault, President, in the chair. New Members.—A. Allison, J. C. Dickinson, W. Cole, F. Finch, G. Graham, D. Holderness, T. Macfarlane, J. E. Moore, Hon. J. McGowan, A. H. V. Morgan, E. K. Mulgan. Lecture.—Mr. E. V. Miller delivered a lecture on “The Ultra-microscope.” The lecturer pointed out that the magnitude of an object which can be rendered visible by the highest power of the microscope is now well understood, and that from the very nature of light we cannot hope for much further improvement. Those objects which are too small to be revealed by the ordinary microscope are consequently called “ultramicroscopic,” and require special modes of treatment to make their presence appreciable. There are two methods at present in existence, which may be called respectively that of ultra-violet light and that of diffraction on a dark field. The lecturer showed that by modification of these two systems it is possible to render visible infinitely smaller things than can be exhibited by the finest microscope, and that even the almost inconceivably small particles suspended in a colloidal solution can be seen, measured, and their movements observed.