REPORT ON HYDRAULICS. — PART 11. 483 



The Commissionei's however conclude, that neither system 

 should be exclusively preferred ; the successful application of 

 either must depend on circumstances ; — that " wherever exten- 

 sive bogs are to be drained, main and minor drains will be re- 

 quired for the purpose to act as receiving drains for the water, 

 with a system of numerous small surface-drains to collect the 

 water in considerable quantities." 



Mr. Edgeworth's report on the seventh district is compre- 

 hensive and ingenious; his instrument for sounding and taking 

 the sections of rivers was capable of giving correct results. 

 Mr. Edgeworth advocated the system of surface-draining instead 

 of deep cuts ; he proposed portable wooden railways to be sup- 

 ported on the bogs by piles for the purposes of conveying manure 

 to the surface, which he states to be similar to the plan adopted 

 by Mr. Roscoe on Chat Moss. His experiments on the com- 

 pression of bogs are, however, very contradictory*. 



The third Report of the Commissioners is confined to a state- 

 ment of former proceedings; and to giving the reports of their 

 engineers on the surveys of 474,808 English acres of bog. 



The fourth and last Report concludes the labours of the Com- 

 missioners, by giving the reports of the engineers, Messrs. 

 Nimmo, Edgeworth, and Griffith, on 305,012 acres of bog, ex- 

 clusive of 500,000 acres of bog in the counties of Kerry and 

 Cork. 



For the improvement of mountain bog, Mr. Nimmo recom- 

 mends irrigation, the advantage of which in reclaiming bogs, 

 he states, has been proved by experience in some few instances 

 in Ireland, but principally in Scotland. 



Mr. Nimmo observes, that wherever a stream flows through a 

 bog it appears to prevent the growth of bog-plants, and the 

 vegetation of wholesome grass is rapid on its banks ; but as this 

 system can only be applied to bogs in elevated situations, he 

 recommends surface-draining for bogs in flat countries, adopting, 



• The author of this paper, when making the survey of the present Liver- 

 pool and Manchester Railway in the year 1825, found that a cubic foot of 

 moss, taken from Chat Moss, weighed 62*24 lbs ; a heap of moss 4 yards by 

 3 yards, and 2^ yards in height, weighing about 22| tons, sunk 18| inches. 



A quantity of moss, 12 inches long and 6 inches square, was put into 

 a box with holes; its weight at first was 12 pounds; after being compressed 

 some time it weighed only 3 J pounds : the moss was found to be reduced to 

 4| inches in thickness. It was further reduced by a compression of 20 tons, and 

 an evaporation by heat to 1^ inch; so that the total loss in weight was 

 iO pounds of water, being in the proportion of five of water to one of vegetable 

 matter, and the compression in bulk of eight to one; and in taking accurate 

 levels of Chat Moss, its surface was found to rise and fall two feet above its 

 average rise in wet weather. 



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