182 
FIFTH REPORT- 1835. 
in contemplation, an early application was made to Capt. Super¬ 
intendent Ross, of the Dockyard, who interested himself in the 
undertaking, and with that kind liberality and courtesy for which 
he is so greatly distinguished, speedily afforded every just en¬ 
couragement to the views of the British Association in this great 
endeavour to advance the interests of science. The hourly re- 
9 / 
gister, therefore, was soon commenced and carried on by the 
Warders and Officers of the Watch stationed at the gate, all 
persons of respectability and character*. It is due to them to 
say, that they have entered with more than common interest 
into the scheme, and have used every exertion to render the ob¬ 
servations as perfect as possible. Little difficulty has hence 
arisen in obtaining the series of thermometric observations in 
the South of England, as contemplated by the Association, 
which for extent and accuracy may perhaps be considered the 
most perfect of any yet recorded. 
The thermometer is placed in an insulated position, just 
within a small circle of grass, about 60 feet above the level of 
the sea, and distant from it about 300 yards : it is sheltered 
from direct and indirect radiation, local heat, humidity, and 
other disturbing causes, by alight screen of latticed wood-work, 
quite open toward the north-east, and painted of a light colour ; 
this screen is small, and is fixed on a single vertical pillar, as 
represented in Plate Y. The lattices round the sides and be¬ 
neath are made in the wav of Venetian blinds, so that there 
is always a free current of air in circulation, and little chance 
of error from the absorption of heat by the screen. The lat¬ 
ticed work below inclines at a sufficient angle to cut oft all re¬ 
flexion from the ground. There is a small sliding index of brass 
attached to the instrument, in the way of a T square ; one arm 
projects over a slate, whilst the other can at any time be made 
to coincide with the surface of the mercury, and thus show with 
9 / ' 
more precision its exact indications. A line may at the same 
time be drawn on the slate, coincident with the position of the 
mercury at the time of an observation; and thus when requi¬ 
site we may again compare the entries made in the register du¬ 
ring the night. The continued habit, however, of registering 
the observations has rendered this now unnecessary. The in¬ 
strument itself is a valuable one; it was obtained from Mr. Cox, 
optician, of Devonport, whose skill in the construction of philo- 
* Mr. Isaac Watts, also of the Dockyard, a gentleman of considerable at¬ 
tainments in science, educated at the late school of Na%'al Architecture at Ports¬ 
mouth, has been so good as to interest himself in the success of this undertaking, 
and by an occasional attendance to the progress of the observations has done 
much in forwarding them. 
