Dr. MacCulloch on a Method of Splitting Rocks by Fire. 47 



the Highlands, the same reasoning applies, as, either peat is 

 seldom far distant, or the land itself furnishes brush- wood and 

 weeds. These are often burnt for no other purpose than 

 that of destroying them, and procuring the ashes and burnt 

 earth attached, which are found to form an useful manure ; 

 while by making this use of them the same produce would be 

 obtained in addition to the other advantages. 



In clearing land by this process, it would be necessary to 

 form previous deposits of fuel in convenient parts of the 

 field, that no impediment might take place during the pro- 

 cess of firing, but that all the labour required for the several 

 parts of the work, may, at one time, be dh'ected to one object 

 only. Thus the labour which, during one period, has been 

 expended in distributing the fuel, will, in the second, be en- 

 gaged in firing the stones ; and, in the third, in splitting them 

 by the wedge, when they will be ready for removal, either by 

 the plug and gin, or by the more common proceedings. 



It will be seen that, in this case, the great saving of labour 

 takes place in the firing, as one man can attend a considerable 

 number of fires over a large space, and thus, in a single day, 

 prepare an extensive tract for the hammer and wedge. Thus, 

 it is calculated, that the firing and the previous labour of col- 

 lecting fuel will not exceed the price of tools and gunpowder, 

 and the comparison will then remain between the time or la- 

 bour required to bore so many mines, or to split the blocks 

 by the wedge. These are data easily ascertained with very 

 little attention ; and if, on more extended trials, the balance 

 in favour of the method used at Loch Ewe shall be found to 

 correspond elsewhere, as it has there done, it will be found a 

 valuable acquisition both to road-makers and to improvers of 

 rough land in the Highlands. 



It remains to be ascertained to what extent the same prac- 

 tice is capable of being applied in splitting solid rocks, no ne- 

 cessity for this having occurred at the place in question. 



It is evident that it will, in this case, be limited in many 

 places, by the form of the rock, as the fire cannot often be 

 effectually applied except to a horizontal surface. But, 

 doubtless, many cases will occur where this practice can be 

 brought into use with economy. 



