1824.] the Purpose of Blasting in Lead Mines. 2Y1 



one side and flat on the other, in this hole, the former being 

 next to the rock, the wedge or stake was driven between until a 

 portion of it split asunder. 



This wedge also was found near the same place 

 with the preceding, of six inches in length, and one 

 and one-fourth inches square, tapering to a point, 

 having a hole one-fourth inch square, through it, at 

 one and a half inches from the top ; this, according to 

 the reports of very old miners, was intended to receive 

 a small rod of iron, by which, one man held, whilst 

 another drove the wedge ; but not used during the 

 life of any present workman. 



At what period the present method of blasting was 

 introduced into these mines cannot be ascertained. A person 

 now residing there, recollects to have heard his father (who died 

 thirty-nine years ago at the age of sixty-seven) say, although it 

 took place before his time, that prior to the pricker and drive-all 

 being used, it was so hazardous an experiment, that two men 

 were specially appointed, whose province it was to visit the dif- 

 ferent workings, for the express purpose of charging and blast- 

 ing, after the holes had been prepared. Another, who, as well 

 as his father and grandfather before him, has been a pickman 

 for sixty years past, has a faint remembrance of hearing very old 

 men say, that formerly stemples were employed, but has no 

 knowledge as to the process, nor ever saw any other mode prac- 

 tised than the present ; but that the stock and feathers had been 

 in use during both the lifetimes of his father and grandfather. 



Article XIII. 



Inquiry how far the Opinions generally entertained of the Inuti- 

 lity of Observations of the Eclipses of Jupiter's Third and 

 Fourth Satellites, are well or ill founded. By J. South, FRS. 



(To the Editor of the Annals of Philosophy.) 



DEAR SIR, niackman-ntreet, Feb. 23, 1824. 



To the advancement of natural knowledge there is probably 

 no one thing so inimical as prejudice, and perhaps there is no 

 science, which has suffered so much from this common enemy to 

 all, as has astronomy. To enumerate the various mischiefs 

 which this busy fiend has inflicted upon this peculiar science 

 would be foreign to the present purpose. Suffice it to say, its 

 baneful effects have been not only felt by physical, but also by 

 practical astronomy. 



After the discovery of telescopes (as might be expected), we find 

 them employed upon Jupiter and his satellites, more than wpon any 



