Book III. 



IMPROVEMENT OF ROCKY SURFACES. 



743 





4522. There are various modes of getting rid of stones. These are generally of such a 

 size as to admit of being conveyed away in carts or other vehicles calculated for the 

 purpose. Some ingenious artificers have constructed machines for raising them, when 

 large. On some occasions, pits have been dug close to large stones, and the latter have 



been turned into the former, at such 



a depth as to lie out of the reach of 



the plough : but it is frequently 



necessary to reduce their size by 



the force of gunpowder before they 



can be removed. Loose stones are 



commonly moved by levers, and 



rolled on a sledge ; but sometimes 



they are raised by a block and 



tackle attached to a triangle with 



a pair of callipers to hold the stone 



(Jig. 703.) The stone may also 



be raised by boring a hole in it 

 obliquely and then inserting an iron bolt with an eye (Jig. 704. \ which, though loose, 

 will yet serve to raise the stone in a perpendicular direction. 



4523. Itichardson's machine for raising large stones (Jig. 705.1 consists of a frame- work supporting a five- 



7nrt /Oi. ""'^ ' ac k' e > with blocks ten inches in dia. 



705 /?ji meter, and a roller seven inches in diame- 



ter turned by two long iron levers. A hole 

 is made in the stone to be raised by means 

 of the tool well known to masons as a 

 jumper; in this hole a simple plug may be 

 driven tightly ; or a compound plug (Jig. 

 706.) may be introduced ; or, what is sim- 

 plest, the hole may be made obliquely. 

 Smith's Compendium of Practical Inven- 

 tions.) 



*4524. The mode of bursting or rending 

 rocks or stones by gunpowder is a simple 

 though dangerous operation. When a hole 

 is to be made in a rock for the purpose of 

 blasting with gunpowder, the prudent work 

 man considers the nature of the rock, and 

 the inclination or dip of the strata, if it is 

 not a detached fragment, and from these 

 determides the calibre, and the depth and 

 direction of the bore or recipient for the 

 gunpowder. According to circumstances, 

 the diameter of the hole varies from half 

 an inch to two inches and a half, the depth 

 from a few inches to many feet, and the 

 direction varies to all the angles from the 

 perpendicular to the horizontal The im- 

 plements for the performance of this ope- 

 ration are rude, and so extremely simple 

 and familiar as hardly to require description ; and the whole operation of boring and blasting rocks is so 

 easily performed, that, in the space of a few weeks, an intelligent labourer may become an expert quarrier. 

 A writer in the Mechanics'' Magazi?ie has proposed to increase the effect of the gunpowder, by widening 

 the lower extremity of the bore, and this lie thinks may be effected, after the bore is made of the proper 

 length, by introducing an instrument with a jointed extremity which would work obliquely. 



4525. The operation of ramming 

 frequently gives rise to accidents ; 

 but a recent improvement, that of 

 using a wadding of loose sand, or of 

 any earthy matter in a dry state, 

 answers all the purposes of the firmest 

 ramming or wadding. It has been 

 used for upwards of ten years at I.ord 

 Elgin's extensive mining operations 

 at Charlestown in Fifeshire, and also 

 in removing immense bodies of rock 

 from the Calton hill at Edinburgh, by 

 Stevenson,an eminent engineer.whose 

 article on the subject of blasting, in 

 the Sup. to the Encyc. Brit, deserves 

 the attention of such as use the pro- 

 cess in working quarries or clearing 

 rocky or stony grounds. 



4526. Dr. Dyce of Aberdeen has 

 communicated to Dr. Brewster's 

 Journal an account of a cheap and 

 effectual method of blasting granite 

 rock, which deserves the particular 

 attention of the owners and workers 

 of quarries. It is beautifully scien- 

 tific, and may be summed up under 

 the three following head: : viz. 1. To 

 ignite the gunpowder at the bottom 

 of the charge, by means of sulphuric 

 acid, charcoal, and sulphur. 2. To 

 take advantage of the propelling power 



