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MONTHLY JOURNAL OF AGRICULTURli 



The pai'tial paring and burning of the head- 

 lands of fields, for the purpose of mixing the 

 ashes and burnt earth with dung in a compost, 

 is a most excellent practice, and often superior 

 to that of using the sods only, without burning 

 them. These sods contain innumerable seeds 

 of weeds, and eggs or maggots of insects, which 

 are not destroyed by the fermentation of the 

 heap, but, on the contrary, are brought to life. 

 The loss of a portion of vegetable matter in the 

 burning is amply compensated by the destruction 

 of these enemies of the future crops. 



It now only remains to take notice of the soils 

 and situations where paring and buraing cannot 

 be recommended. Wherever the soil is v^ry 

 loose from a great proportion of silicious sand in 

 its composition, and is held together chiefly by 

 the slender roots which run through it, the burn- 

 ing would destroy the whole of the vegetable 

 matter ; for none of the volatile parts which the 

 lire dis.sipates or generates would be retained or 

 absorbed, but would pass through the loose 

 sand in the same way tliat water would. Here 

 then would be actual destruction ; and the resi- 

 due would be a mere barren silicious sand, 

 much worse and more porous than it was when 

 held together by the roots. The only way to 

 bring such soils into cultivation is to put clay or 

 marl on them, and to force vegetation by means 

 of liquid manures, chiefly the urine of animals, 

 consolidating them by every means applicable, 

 BO that they may retain moisture, and that the 



manure may not be washed through by the rains. 

 Such soils may be improved, but they are the 

 most ungrateful of any ; and it is only necessity 

 and indefatigable industry which can make 

 them produce any crops. 



It is very easy to ascertain whether any soil 

 will be improved or not by paring and burning. 

 A few sods may be taken and exposed to heat 

 in an iron pot closely covered over, or in a large 

 crucible : the heat should not be so great as to 

 produce light, but should be kept up for a con- 

 siderable time, till the sods are consumed. If 

 the ashes are red, and the whole is a line pow- 

 der, with particles of charcoal in it, the soil from 

 which it w^as taken may be safely pared and 

 burnt, especially if it forms a mud with water, 

 and the earth is not readily deposited. But if 

 it feels gritty, lets the water readily through, 

 and is soon deposited when mixed with it, 

 burning will not be advantageous. This is the 

 evident result of the principles laid down be- 

 fore. 



On the whole, the operation of paring and 

 burning, when judiciously applied and proper- 

 ly performed, is a most excellent and cheap im- 

 provement of certain soils, and it will never di- 

 minish their fertility, if they are properly culti- 

 vated and manured, and a judicious succession 

 of crops is adopted ; but on the conti-ary it will 

 improve their quality and texture, and make 

 them more productive. 



THE CENTRE OF GRAVITY. 



We have heretofore alluded, but only inci- 

 dentally and scarcely in a way to make our- 

 selves understood, to the various .studies which, 

 (although the connexion is not at first apparent,) 

 are yet necessarj' to the most efficient practice 

 of the Agricultural art. Among these, the gen- 

 eral principle of Mechanics should be esteemed 

 as of the highest importance. We will suppose 

 them to be inculcated in Common Schools, by 

 means of lectures and illustrations, clear and 

 simple as we find the following, for instance, in 



Fig 



part of one of Z>r. LarAner's Lectures omsE 

 Centke of Gravity ; and who does not see 

 how useful through life would be tuition of this 

 sort: 



When the line of direction falls within the 

 base, bodies will always stand tinu, but not with 

 the same degree of stability. In general, the 

 stability depends on the hight which the centre 

 of gravity must be elevated before the body can 

 be overthrown. The greater this hight is, the 

 greater in the same proportion will be the sta- 

 bility. 



Let BAG, fig. 23, be a pyramid, the centre 

 of gravity being at G. To turn this over the 

 edge B, the centre of gravity must be carried 

 over the arch G E, and must therefore be raised 

 through the hight H E. If, however, the pyr- 

 amid wen; taller relatively to its base, as in fig. 

 2-1, the hight H E would be proportionally less ; 

 and if the base were very small in reference to 

 the hight, as in fig. 25, the hight H E would 

 (404 



be very small, and a slight force would throw 

 it over the edge B. 



It is obvious that the same observations may 

 be applied to all figures whatever, the conclu- 

 sions just deduced depending only on the dis- 

 tance of the line of direction from the edge of 

 the base, and the hight of the centre of gravity 

 above it. 



Hence we may perceive the pnnciplc on 



