The result of the investigations, set on foot by the com missioners, with regard to the extent of the bogs in Ireland, is given in their fourth report, laid before Parliament in the session of 1813-14, as follows :— Besides, there arc the three mountain districts of Wick low, Erris, and Cunnemera, which contain, respectively, 97,000, 170,090, and 120,000 acres ; and in the two last districts, there are of mountain peat soil, respectively, 155,500 and 200,000 acres. The extent in Wicklow has not been ascertained. The mountain peat soil in other parts of Ireland is supposed to amount to about 900.000 acres. Of the hogs under 500 acres, there are about 90 in the county of Cavan alone, containing 17,6(0 acres in all ; and the commissioners suppose, that the other parts of Ireland cannot contain less than ten times as great an extent of these lesser bogs as the single county of Cavan.
"Flom all the above data (the commissioners observe) we can confidently pronounce, that the extent of peat soil to Ireland exceeds 2,830,000 English acres, of which we have shewn at least 1,576,000 to consist of flat red bog. The remaining 1.255,000 acres form the covering of moun tains." The strata of which the bogs in Ireland in general con sist, or which lie below them, will more properly be con sidered when tie come to trcat of the geology of Ireland. ,1t present we shall extract from the reports of the corn missi..ners the heights of some of the bogs.
In that which is generally called the Bog of Allan, the highest summit of Lullymere hog is 256 feet above high water mat k in Dublin Bay, the lowest point 214 feet ; the highest point of Timahoe bog 289, the lowest point 232 ; the highest summit of the Bog of Mounds 296, the lowest point 254 ; and the highest point of Chile bog 298, and the lowest point 255 feet above high water mark in Dub lin Bay. The greatest height of the bogs on the west of the Shannon, above Lough Rce, is 76 feet, the lowest point 29 feet ; the greatest depth 43 feet, the least depth 2. feet. The greatest height of the bogs on the east of this river, in the counties of Longford and Leitrim, is 114 feet, the lowest point 30 feet ; the greatest depth 43 feet, and the least 30 lent. The greatest height of the surface of the bogs in the district of the Boyne, above the sea at high wa ter mark in Dublin Bay, is 336 feet, the least height 218 ; the greatest depth 40, the average depth 22 to 25 feet. The greatest height of the surface of the bogs to the northward of the Brusna is 274 feet, the least height 114 ; the greatest depth 44, the average depth 30. The great
est height of those to the southward of this river is 3IC feet, the least height I l 1 ; the greatest depth 45, the ave rage 22 to 25. The greatest height of the bogs in the district of the Inny and Lough Ree is 253 feet, the least 176 ; the greatest depth 47 feet, the average 30 to 35 feet.
As it is obviously a matter of the highest national im portance, that these bogs, if possible, should be reclaimed, and rendered capable of conducing to the sustenance of man, the commissionets particularly directed their atten tion and investigations to ascertain how far, and by what thi3 practicable. They remark, that " peat moss ought to be consideicd a3 partaking, in its general . nature, of the property of sponge completely saturated with water, and giving rise to different streams and rivers for the discharge of the surplus waters which it receives from rain or snow." In the district of Allan, as well as in many other districts, these streams have worn their channels through the substance of the bog down to the clay or limestone gravel underneath, dividing the bog into distinct masses, and presenting in themselves the most. proper situations for the main drains ; and which, with the assistance of art, may be rendered effectual for that purpose.
Another circumstance is favourable to this great un dertaking. Their surfaces, in general, are by no means level, but with planes of inclination amply sufficient for their drainage. The highest summit of any part of the bogs in the eastern district of Allan is 298 feet above the level of the sea, taken at an ordinary spring tide in the Bay of Dublin ; and the lowest point is 214 feet above the same level. In the Bog of Timahoe, a part of its water is discharged into the sea at Drogheda, and another part below Waterford.
We have thus stated the two grand facts on which the commissioners rested the practicability, and indeed the facility, of effecting the drainage of the bogs of Ireland, and on which they accordingly farmed their plans. That they will be successful, there can be little doubt, provided they are executed with skill, and sufficient funds are allow ed. And as far as the estimates of the engineers may be depended upon, the expence will be amply counterbalanced by the quantity of useful land recovered. The estimate for draining the eastern district of the Bog of Allan is 147,052, 6s. 11d., and the quantity of land which would be gained is 36,430 English acres, or about 401. an acre.