182 M‘Sweeny, on the Climate of Ireland. 
« 
this be admitted, it follows as a consequence, that Ireland must have experienced, at 
one period, a climate of a high temperature. In Jameson’s Edinburgh Philoso- 
phical Journal, for 1828, vol. xviii., an extract of a lecture on climate, delivered by 
Humboldt, is given, in which are to be found many valuable observations. He ob- 
serves, that the time is passed, when persons were satisfied with some undefined views 
of the difference of climates, and when all the modifications of temperature were 
ascribed either to the shelter afforded by ridges of mountains, or to the various eleva- 
tions of the earth. He remarks, that remarkable differences of climates are perceived 
in large tracts of country under the same latitude, and on the same level above the 
surface of the sea, which do not arise from the trifling influence of individual localities ; 
but are subject to general laws determined by the form of the continents in general, 
by their outlines, by the state of their swrface, but particularly by their respective 
positions, and the proportion of their size to the neighbouring seas. [rom the pro- 
portion of the size of Ireland to the vast Atlantic, no wonder that our winters should 
be mild, and that our summers should not be very warm. 
The influence of the sea on climate is a matter that admits of no dispute ; but other 
matters relating to temperature are involved in obscurity—for instance, the occa- 
sional visitation of very severe winters. Are the supporters of the doctrine of central 
heat, prepared to maintain, that its agency in some winters is less than in others ? Cor- 
dier supposes the thickness of the crust of the earth to vary in different places, and 
explains on the principle of central heat, the difference of climate in countries in the 
same latitude. This curious subject is engaging the attention of the scientific world, 
but it must be acknowledged, that the occasional return of very severe winters, and 
of extremely hot summers, does not at present admit of any satisfactory explanation. 
Many writers, by selecting from the works of the ancients, passages which treat of 
severe cold, have led to an almost general belief, that the climate of Europe has very 
much changed: but a person residing in a distant country would form a very erro- 
neous notion of the climate of England, if he were only to read a number of accounts 
of the Thames having been frozen over at different times, and the extraordinary years 
are these that are most likely to be recorded. Doctor Patterson had the courage, in his 
work on the climate of Ireland, to deny the asserted change in the climate of Italy. 
It is a matter of importance in this inquiry to investigate, if any change of conse- 
quence has taken place in the climate of the continent; if it could be shown that an 
important change has taken place there, it would be but reasonable to suppose a 
change also in the climate of Ireland. But let the climate of Europe in general be 
what it may, at any time, it may be safely asserted, that Ireland, from not having 
mountains of great height when compared with those of other countries from its insular 
situation in a temperate zone, from its being exposed to the vapours of the Atlantic, 
must from the most remote periods have possessed a climate, mild and moist, when 
compared with that of the rest of Europe. 
