=, 
230. M‘Sweeny, on the Climate of Ireland. 
evident that after a fall of snow, some of it would lie a considerable time undis- 
solyed in these trenches. 
The appearance of frost is a signal for the Irish peasant to dig out his potatoes, 
and consequently to obliterate the trenches. The level dark-coloured ground, which 
remains after the potatoe crop, is well adapted for melting snow. The sun exerts its 
influence to great advantage on a dark surface, according to the experiments of 
Franklin ; and at night, fallow ground of this description, is, according to the expe- 
riments of Dr. Wells, particularly unfavourable for the production of hoar frost. 
Thus modern science is in favour of popular opinion. 
The potatoe culture shades the ground in summer also, in the following manner : 
A number of the hills of Ireland lie east and west ; the potatoe trenches, which are 
so many drains, run at right angles to the tops of these hills, for the purpose of con- 
veying off superfluous water ; the rays of the sun from east to west do not therefore 
traverse directly these trenches, and thus the beds, independently of the stalks, cause 
ashade. In this way a great portion of the surface of Ireland is shaded in summer, 
but particularly by the luxuriant stalks of potatoes, that meet the eye of the traveller 
in every direction. 
The potatoe culture has also wonderfully increased the number of enclosures, and 
hedge rows, and has consequently added to the shading of the ground in summer, in 
every direction, even up to the tops of mountains. Hedge rows also afford shelter to 
cattle in winter. Smith, in his History of Kerry, stated that cattle in his time some- 
times perished on the mountains in severe winters. 
Before the general cultivation of the potatoe for the food of the people, (in the re- 
collection of many, oaten bread constituted a considerable portion of their diet,) large 
tracts of pasture ground denuded of timber, and not intersected by hedges, must have 
been liable to be parched in summer. ‘The bed and trench plan of: culture, the fa- 
vourite system with our peasantry, is admirably adapted for draining this moist island, 
and for mixing clay with a peaty surface. 
In winter, bogs and shallow pools, were easily frozen at night, and served as reser- 
voirs of cold on the following day. According to the experiments of Doctor Wells, 
grass is particularly liable to be covered with dew and hoar frost. ‘The extensive 
system of pasture formerly followed in Ireland, must have often presented a large sur- 
face of hoar frost to the action of the morning’s sun. 
A considerable portion of the heat of the morning’s sun must have been therefore 
expended, in thawing the ice on shallow pools, and in bogs, and in melting the hoar 
frost, formed on the grass during the night. 
If, notwithstanding the draining of swamps, the reclaiming of bogs, and the ame- 
lioration of the soil by manures, and by more judicious cultivation, it’should be con- 
tended, that on an average of years, the winters at present are exactly as cold as they 
were previous to the general cultivation of the potatoe; it would imply, that the 
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