330 PROFESSOR FORBES ON THE CLIMATE OF EDINBURGH. 
11. The two sets of observations are each consistent among themselves; but the 
average difference of the two series, amounting to 1°°6 in excess for the mean 
temperature of Hawkhill above Edinburgh, is greater than the difference of level 
and exposure would seem to warrant. Even after applying a correction of +0°-25 
to the Edinburgh observations, deduced from Marrine’s estimate of blood heat 
(Art. 5), these averages appear to be too low, whilst those of the Hawkhill 
observations agree well with the modern ones contained in the sequel of this paper. * 
12. Professor PLayrair appears to have commenced in 1794 a register in Wind- 
mill Street (near George Square), Edinburgh, 265 feet. above the level of the sea. 
The results are published in the Edinburgh Transactions, Vols. IV. and V., from 
1794 to 1799 both inclusive. The hours of observation were nearly 8, 2, and 10 
(not 8, 12, and 10, as stated by M. Dove}), the middle observation being chosen 
so as to fall nearly at the moment of highest temperature. 
Mean Annual Temperature of Edinburgh. 



| Years. Playfair, 8, 2, and 10h, Adie, 8" and 8}. Difference. 
| 
1794 50°32 ie 
~ 1795 47°75 45:67 
1796 48:10 46°46 
bel og 48°04 46°33 
1798 49:28 47-59 
1799 46:13 44°44 


The difference is striking, and nearly constant. Sir D. Brewster attributes it to 
the radiation of heat from neighbouring houses at the midday observation.t At 
all events, Professor PLAYFatr’s observations seem to be in error. 
13. The only farther contribution I have to make to the older series of obser- 
vations is to mention that in Mr Apie’s earliest Register Book, mentioned below, 
I find a memorandum that the mean temperature of the year 1787 was 46°44 ; 
of 1788, 46°°191; and of 1789, 46°°573; but the authority is not given. 
Sect. 2. On Mr Adie’s Thermometrical Observations generally, and their Reduction. 
14. The observations of Mr Apie on the temperature of Edinburgh have 
hitherto been known by their periodical publication for some years, commencing 
with 1824, in Sir D. BrewstTEr’s “ Edinburgh Journal of Science,” from whence 
they have been quoted by M. Dove in his various writings. 
* Farther references to Mr Maccowan’s observations will be found in the ‘¢ London Philoso- 
phical Transactions” for 1775, and in the Edinburgh Transactions, vol. iv. p. 214; but I have not 
been able to discover any continuation of the observations later than 1776. 
+ Not unnaturally, since in the Tables themselves the word “noon” is used to denote the 
midday observation. Compare p. 214 of the paper in vol. iv. of the Transactions, 
t Edin. Trans. ix. p. 209. 
