ON THE REDUCTION OF METEOROLOGICAL OBSERVATIONS. 71] 
The minimum and maximum of the 17th and 21st hours are hardly more 
marked than what the periodical oscillations will account for. 
Hanover is, as usual, peculiar. The slight tendency to fall as far as the 
5th hour, and preservation of a level from thence to the 12th, indeed would 
tend to connect it with the former system, but instead of going on thence to 
a minitium, the curve begins thence to rise slowly but steadily as far as the 
21st hour (through 0:03 inch), when again a slight but abrupt protuberance 
at the 22nd hour recals the corresponding feature in the Geneva group. 
In Britain the Ashurst curve is interrupted from the 7th to the 18th hour, 
but where traced is nearly identical with those of London, Greenwich, and 
Blackheath ; and we may add also, with slight modifications, of Oxford. All 
these four curves agree in a minimum between the hours 0 and 1 of a very 
flattened character, followed by a gentle rise of about 0°08 inch, which con- 
tinues to the 18th hour, where in London aid Ashurst a trace of the Geneva 
minimum occurs, followed, in these as well as at Oxford, by the protuberance 
already noticed in the Continental system. 
Proceeding thence to Halifax, Edinburgh and Markree, the range in- 
creases, and the curves undergo a great change of character. In the cutves 
of all three, indeed, a minimum in the beginning of the series, and a rapid 
downward tendency at its termination, connect them with the other members 
of the group, but in the intermediate hours their course is very different. 
‘Halifax rises to a bold maximum at 3 hours, through a range of 0°20 inch, 
after which it descends again with equal decision to the end of the term. 
Edinburgh is marked through its whole course with sudden ascents and de- 
scents, of a very desultory character, neglecting which, if a flowing curve be 
drawn, we find it rise, as in the case of Halifax, to a single strong maximum 
at 10 hours (or 5 hours earlier than at Halifax), and thence descending again 
to and beyond its initial level, giving a total range of 0°13 inch. The wind, 
which was moderate or light at Edinburgh during the afternoon of the 21st, 
gives no clue to the explanation of an extremely abrupt zigzag in the curve at 
3 hours and 4 hours, which therefore have probably originated in misreadings. 
The Markree curve rises from its minimum at 0 hour to a maximum at 
12 hours, through 0°12 inch, thence retains its level nearly unchanged till 
between 17 and 18 hours, when the rise to the diurnal maximum commences, 
followed by a pretty decided slope downward, which beyond the limits of the 
projected curve (as the continuance of the observations show) became rapid, 
and was accompanied by a gale of wind from the west. A heavy gale from 
the same quarter is also noted at Halifax attending the decline of the baro- 
meter at that station, and at Edinburgh it is also recorded as freshening to a 
moderate and ultimately to a “high” wind ; the strength of the wind in each 
ease increasing with the barometric depression. 
March 1837.—Markree, Halifax, Edinburgh, London, Greenwich, Brus- 
sels, Hanover, Geneva, St. Jean de Maurienne, Turin, Kremsiniinster, Cadiz, 
Gibraltar, Tangier. 
- This term presents nothing very distinct. The barometric ranges for the 
most part small, and where moderately large not well agreeing. The follow- 
ing may be noted as features of some interest. 
Diurnal oscillations —Very perceptible at London, Greenwich, Brussels, 
Geneva, Kremsmiinster. 
Range.—Very small at Brussels, Hanover, Gibraltar, Tangier. Greatest 
at Markree, Halifax, Kremsmiinster. The nodal character of Brussels may 
be regarded as supported by the observations of this term on the whole. 
Sudden and broken undulatory movements.—Remarkable at Edinburgh 
from the 12th to the 17th hour. 
