452 Dr. Burney’s Meteorological Observations. [June, 
was ;th of an inch greater: this, added to what has been 
before mentioned, makes the annual range 21 inches. 
Horizontal Day and Night Thermometer. 
The mean temperature of the extremes of heat and cold, as 
ascertained by this thermometer, which seems preferable for 
general observations to that on Six’s construction, is 52:79° ; 
that is, 21° higher than in the preceding year. But some doubts 
are entertained as to the accuracy of this way of obtaining the true 
mean temperature, although it has hitherto been generally adopted 
by those who have published their meteorological diaries trom 
time to time for the benefit of the science. To obtain the true 
mean temperature of any place in Britain, four observations at 
least should be taken every 24 hours ; namely, at eight, a.m. 
eight, p.m. and the maxzmum and minimum: the mean of these 
observations would approximate nearer to the truth than the mean 
of the extremes only. 
Taking four observations each day, however irksome it may 
be considered, in order to bring out the annual result, is abso- 
lutely necessary, on account of the sudden transitions which are 
so frequently experienced by the thermometer as well as by our 
own feelings ; and because the average of the greatest number’ 
of thermometrical observations in such a variable climate must 
necessarily come nearest to the truth. According to this mode 
of calculating, the annual mean temperature is 4ths of a degree 
less than that shown in the table, as the mean of the daily 
extremes of heat and cold. 
Those who have not got self-registering thermometets, nor 
time to register more than once a day, and yet wish to know 
the mean temperature of their own places of abode, there is 
reason to believe that if they were to take a daily observation at 
half-past eight, a.m. it would obtain the annual mean tempera- 
ture nearly as correct as the mean of the daily extremes only, 
particularly if the situation be contiguous to the sea, and the 
thermometer properly shaded from the sun’s rays, and in a direct 
northern aspect. 
Comparison of the ree mean Temperatures of Gosport and 
Tottenham near London, for the Years 1817 and 1818. 
The mean temperature of Gosport for the last two years taken 
together is 516°: of Tottenham, from the meteorological tables 
of Luke Howard, Esq. in the Annals of Philosophy, 49-4° ; dif- 
ference 21°. Now as Gosport is rather more than 2ds of a 
degree further to the south than Tottenham, its mean tempera- 
ture should be nearly a degree higher, because the mean 
temperatures of places on a direct parallel of latitude from 55° 
to 45° north have been found by experiments to increase nearly 
in the same ratio as the degree of that space of latitude. But as 
: 3 
