326 
LIEUT.-COLONEL SYKES’S DISCUSSION OF METEOROLOGICAL 
sarily be unsatisfactory. In 1847 meteorological tables appear in the Journal of the 
Asiatic Society of Bengal from the same source as those used by the Horticultural 
Society in the preceding years, namely, from the office of the Deputy Surveyor- 
General in Calcutta, but they were even of less use than the preceding tables, for they 
had but two daily records, namely, at and 4 p.m., and the records were other- 
wise useless for determining the absolute range of the thermometer, as there was only 
a record of the maximum temperature and no minimum. In 1848 more elaborate 
tables make their appearance, containing two-hourly records from sunrise to sunset, 
at sunrise, 9^ a.m., noon, 2*’ 40™ p.m., 4 p.m., and sunset, together with the indications of 
a maximum and minimum thermometer, but without any observations after sunset. 
This is an improvement upon the former records, but falls short of the requisites for 
scientific purposes. The maximum and minimum thermometer certainly gives the 
range of temperature, but does not give the hours of the occurrence of the maxima and 
minima. Mean temperatures deduced from a maximum and minimum thermometer 
may possibly be true; but an arithmetical mean from two extreme observations daily 
would be incorrect, unless the increment and decrement of heat from a mean point 
were regular, which is known to be rarely the case. Annual mean temperatures de- 
duced from formulae, of which the latitude is the element, are often fallacious ; for 
independently of the great discrepancies in mean temperatures between America and 
Europe on the same parallels of latitude, and as indicated also by isothermal lines in 
Europe, there are places differing little in longitude where the annual mean tempe- 
rature is higher than at places nearer to the equator, both within and without the 
tropics : taking an instance from Dove’s temperature tables, we have the following ; — 
1 Aberdeen . 
o i 
Latitude 57 9 
0 
Mean temperature 49' 18 
2 Dundee . . 
Latitude 56 27 
Mean temperature 51'94 
3 Edinburgh . 
Latitude 55 58 
Mean temperature 47' 13 
4 Liverpool . 
Latitude 53 25 
Mean temperature 50'80 
5 London . . 
Latitude 51 30 
Mean temperature 50*83, or 49'7 by Glaisher. 
Aberdeen, therefore, nearly six degrees north of London, has almost the same mean 
temperature as London : and Edinburgh, intermediate between both, has a lower 
mean temperature than either. Dundee, five degrees north of London, has abso- 
lutely a higher mean temperature ; and Liverpool, two degrees north of London, has 
the same mean temperature. In the tropics similar instances are found. 
Calcutta . . . 
. . Latitude 
22 34 40 
Mean temperature 
83-72 
Bombay . . . 
. Latitude 
18 55 42 
Mean temperature 
81-1 
Madras . . . 
. . Latitude 
13 4 10 
Mean temperature 
82-42 
Aden .... 
12 46 26 
Mean temperature 
80*2 
In this case Calcutta, 9 degrees north of Madras and 3^ of Bombay, has a higher 
mean temperature than either ; and Aden, in a lower latitude than any of the places. 
