261 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
1 mm., as the limit of resolving power. This result, e ^ 0 • 5 - , is the 
a 
same as that obtained by Helmholtz in the case of self-illuminating 
objects and full aperture ; so that even if it were possible to make all 
microscopic objects self-illuminating and to observe them with full 
aperture, no advantage would be gained over observation with as narrow 
as possible and extremely oblique illumination. 
(6) Miscellaneous. 
Liverpool Microscopical Society. — From the twenty-fifth Annual 
Report * of this Society we are glad to learn that its affairs are prosper- 
ing, and that the ordinary meetings have been well attended. A new 
departure is the holding of field meetings during the summer months. 
Microscopical Society of Calcutta. — We are glad to learn from the 
sixth Report of this Society (for the year 1893) that its meetings have 
been well attended, and that the finances are in a more satisfactory con- 
dition than they have ever been ; the always present aliquid amari is, 
in this case, the regret felt at the death of the President, Prof. Wood- 
Mason. 
The late Mr. C. Haughton Gill, F.R.M.S. — We regret to announce 
the sudden death, on February 21st, from heart disease, of Mr. C. 
Haughton Gill. Mr. Gill was born at Wells on the 12th June, 1841. 
He received the greater part of his scientific education at University 
College, London, and in 1858, at the age of seventeen years, gained 
the Gold Medal for Chemistry. The following year he took the Silver 
Medal for Analytical Chemistry, and about two years afterwards he was 
appointed assistant to Dr. A. W. Williamson, then Professor of Chemistry 
at the College. He remained at the College about fifteen years, when 
he was offered and accepted the appointment of analytical chemist and 
scientific manager to the firm of David Martineau and Sons, sugar 
refiners ; .when the business was a few years back turned into a limited 
company Mr. Gill was made the managing director, and from this 
position he retired only a few months ago. 
While at University College Mr. Gill published a text-book of 
chemistry for schools, which is still esteemed as a text-book. 
Some five years ago Mr. Gill devoted the greater part of his time to 
microscopical research, chiefly in connection with the life-history of the 
Diatomacese, and on this subject he made some important discoveries, 
which he communicated to our own and other Societies. But his interest 
in microscopy was wide and deep. 
Mr. Gill joined the Society in 1889, and was elected a member of 
the Council in February of last year ; he was also a Fellow of the 
Chemical Society and a member of the Quekett Microscopical Club. 
The following are the papers which Mr. Gill contributed to the 
Journal of the Society : — 
1889. Preparing Diatoms, pp. 834-5. 
1890. On some Methods of Preparing Diatoms so as to exhibit 
clearly the Nature of their Markings, pp. 425-8, plate VII. 
Liverpool, 1894, 8vo, xii. pp. 
