The British Association. 
[October, 
524 
case the observations convinced him that the parallax was 
constantly less than one second, and most probably did not 
exceed half a second. It would therefore be understood 
that Lhe results were purely negative so far as the immediate 
objeCt in view was concerned, as they did not suggest the 
existence of any parallax worth following up. The principle 
upon which the reconnoitring observations were conducted 
was this— -the effeCt of annual parallax upon a star was to 
make the apparent place of the star describe a minute ellipse, 
of which the mean place of the star occupied the centre. 
The star was observed twice. At the first observation the 
star was at or near one of the extremities of the major axis 
of the ellipse ; at the second observation it was at the other 
extremity-— so that the observations were so arranged that 
in each case parallax would have the greatest effedt it was 
capable of producing. 
Prof. H. Hennessy read a paper “ On the Climate of the 
British Islands.” When he first made his investigations on 
this subject he was led to the conclusion that the distribution 
would be represented by isothermal lines having a certain 
parallelism to the coast line of these islands. These iso- 
thermal lines had been laid down from aCtual observation, 
because he had found that the law of increase and decrease 
of temperature, in going inland over a table land or flat 
country, was so extremely slow that it was perfectly absurd 
to use the co-efficient of one degree to 300 feet, which had 
been obtained by balloons. The aCtual results confirmed in 
the minutest particulars the theory of isothermal lines which 
he propounded years ago, and he believed that the more 
observations were multiplied not only in these islands, but 
in New Zealand, Tasmania, and similar places, the more 
would it be found that his theory was correct. The islands, 
however, must have their coasts bathed by oceanic currents 
of a high temperature. The isothermal lines for Ireland 
showed that the distribution of temperature was more influ- 
enced by the sea than by latitude. 
Other papers read were “ On a Diagonal Eyepiece, re= 
quired in certain Optical Experiments,” by Prof. G. Forbes; 
“ On New Magnetic Figures,” by Dr. S. P. Thompson ; 
“ On Dimensional Equations,” by Prof. James Thomson; 
“ On a New Form of EleCtro-Registering Apparatus,” and 
“ On an Isochronous Pendulum,” by Mr. Denny Lane ; “ On 
the Variability of Standard of Height,” by Mr. J. E. Hil- 
gard ; and “ On Lightning Conductors,” by Mr. R. An- 
derson. 
