of Edinburgh^ Session 1865-66. 
573 
Monday, l^th February 1866. 
Sm DAVID BEEWSTER, President, in tlie Chair. 
The following Communications were read : — 
1. Report on the Hourly Observations made at Leith Fort 
in 1826 and 1827, by Direction of the Society. By Sir 
David Brewster, K.H , D.C.L., F.R.S., &c. 
In 1823 the Royal Society established a register of hourly ob- 
servations of the thermometer at Leith Fort. They were made by 
the non-commissioned officers of artillery, and were continued for 
four years, from 1824 to 1827 inclusive. A report on these obser- 
vations for the years 1824 and 1825 was published in the tenth vo- 
lume of the Society’s Transactions ; but from causes to which it is 
unnecessary to refer, the report on the observations of 1826 and 
1827 were not then published. 
The great interest which was attached to meteorological obser- 
vations, but specially to those made every hour, has induced the 
author to publish the results which he has obtained from the 
original registers in the Library of the Society. 
The agreement of these results, with those obtained from the 
observations in 1824 and 1825, is very remarkable, 
2. On a New Property of the Retina. By Sir David 
Brewster, K.H., D.C.L., F.R.S., &c. 
In a paper on hemiopsy,* the author had shown that the parts of 
the retina affected with this disease were susceptible of luminous im- 
pressions and insensible to visual ones, and that the light by which 
they were impressed was derived by irradiation from the adjacent 
parts of the retina. The parts of the retina affected with hemiopsy 
were, however, so small, so irregularly distributed, and the pheno- 
menon of such short duration, that it was difficult to study it and 
deduce any satisfactory results. 
From an accidental observation the author discovered that a 
^ Transactions, vol. xxiv. p. 15. 
