434 Weather Prophecies. [October, 
laws the theory of the wind is founded. Thus we know that 
a rise in the barometer, together with a fallin temperature, as 
shown by the thermometer, indicates the approach of a cold 
northerly current of air; while a fall of the mercury in the 
barometer, with a rise of that in the thermometer, indicates 
that a southerly or warm air current is on its way. Northerly 
currents may include winds from the north-west and north- 
east, as well as from the north; similarly, southerly currents 
may include winds from the south, south-east, or south- 
west. When the barometer rises whilst a north-east wind is 
blowing, with prevalent hail, rain, or snow, there may be no 
change. Of barometrical indications alone, it is generally 
known that a rapid rise portends changeable weather; a 
slow rise, the contrary ; a rapid fall, heavy wind, rain, and 
snow; while a fluctuating height of the column of mercury 
indicates unsteady weather. With a heavy gale of wind in 
the east or south-east, changing south, the barometrical 
column may fal! until the wind shifts its quarter. Upon 
such observations did Admiral Fitzroy base his code of 
instructions, now to be found by the side of every baro- 
meter, his forecasts depending on the indications of the 
barometer and thermometer, with observations as to the 
direction and force of the wind with regard to time and 
place, and its previous course taken altogether. These 
indications are thus not absolute, but relative to the pre- 
ceding state of the weather. But also these indications are 
valid for only a short interval before the actual advent of 
the storm ; and in some instances, as in the Hyperborean 
storm of 2nd and 3rd October, 1860, the interval is too 
short for any advantage to be taken of the notice. The 
particulars of this storm, which presents in true character 
the difficulties which the meteorologist must encounter, are 
too interesting to be omitted, and we shortly recount them 
from the complete and admirably-conducted investigation 
published by Professor C. Piazzi Smyth, in the Annals of 
Scottish Meteorology for 1856 to 1871. The term Hyfer- 
borean has been employed to prevent confusion with tropical 
hurricanes; it has also been called, from its essential 
locality, the Edinburgh storm. We have to consider only 
the practical lessons to be deduced from the observations of 
this storm; the account of the actual observations must be 
read from the before-mentioned report of Professor Piazzi 
Smyth. First, then, the barometric notice was insufficient 
and too local to be of service, while the storm was too quick 
in its movements. St. Hilda is the most westerly station ; 
and even if the storm could have been telegraphed thence, 
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