Dr. MacCulloch on a Method of Splitting Rocks by Fire. 45 



for every large stone ; and in most parts of the Highlands, 

 or of Scotland in general, this is nearly a day's labour for a 

 man, on account of the time expended in coming to the 

 ground and in returning. To this expense, however, must 

 be added, not only the price of the gunpowder, but that of 

 sharpening the gads, which is considerable, and the other 

 wear and tear of tools. I cannot here procure an exact esti- 

 mate of these expenses, nor is it material, as it will easily be 

 calculated by all those who have an interest in doing so, or 

 have such work in hand. I need only add, that as, in many 

 cases, the quantity of such stones on ground otherwise fit for 

 cultivation is enormous, it is material to find out the means 

 of diminishing an expense which may exceed the fee-simple 

 of the land when cleared. The same reasoning applies to 

 the Highland roads, which, from their expensive construc- 

 tion, trench so deeply on the funds provided for them, that 

 nothing remains to replace the accidents arising from tor- 

 rents or other causes, or for the purposes of ordinary repairs. 



The contractor for a road from Loch Ewe to Gerloch, 

 who resides at this place, finding it difficult to carry on his 

 work at the contract price, has abandoned the process of 

 blasting, and has had recourse to fire alone ; and in this way 

 he has now conducted .his road for some miles with a great 

 saving both of time and labour. Whether he has had any 

 precursor, except Hannibal, in this practice, I know not, as I 

 have not found it in use elsewhere in any part of Scotland ; 

 but he appears at any rate to have the merit of an original 

 inventor, as he had heard neither of any predecessor nor rival 

 in his art. 



In conducting the process, a fire of peat is made on the 

 surface of the stone, and being then secured at the margin 

 by stones and turf, it is kept in activity for five or six hours. 

 At the beginning of his career, when the fire was extinguish- 

 ed, Mr. Mackenzie was in the habit of throwing water on the 

 rock, which was then found to open in different places, in 

 such a manner as easily to admit a wedge or two, and thus 

 to be split by a few blows of the sledge. But finding, in 

 some situations, that it was difficult to procure water, and 

 that the expense was thus materially increased, he abandoned 



