Bisbee daily review., 1915-03-14
INSPIRE CAUSES IN BLASTING
 EXPLAINED
Mining Expert Goes Into De
 tail as to the Causes of Many Misfires Which Have
 Caused Accidents.

2
 Wherever high explosives are used, mislres or missed holes are a constant source of danger expense, and annoyance. Many horrible acc cidents are caused through their de- tonation by tools in the hands of workmen. Valuable time is lost in [ searching for missed holes and in repriming and firing them and in waiting for the smoke to clear away before resuming work in the heading; Co say nothing of the failure of bat tery of holes to break its proper ! footsge through the mishre of a lead | ing hole. The causes and prevention Of this kind of trouble are common subjects for earnest thought and dis cussion, participated in by everyone concerned. from 'mucker' 70 superin- tendent.
 The Controlling Factors
 The numerous elements involved in the preparation and blasting of a round of holes give many possibi- lities for unfayorable conditions. or | defects in workmanship. any one which may lead to a misfre. These elements may be enumerated as fol- lows: nature of the ground. pres ence of ground-water; quality and grade Of powder; preparation of the fuse and cap; preparation and posi- ton of the primer; method of load ] ing the hole; arrangement of eN- posed part of the fuse and un- avoidable circumstances.
 All of these factors have been 1 studied and made the subject of help ful and enlightening reports by yari- ous writers in the technical press. by the U. s. Bureau of Mines. and by the powder manufacturers; but it Is my belief that there is room for further emphasis on the subject of care in the preparation of the fuse and cap. In the course of ten years | close observation of blasting condi- l tions. involving daily inspection of newly blasted working faces. l have come to the conclusion that a large | lA lbA AlbAA bA Alll0NNA llhlfN In NuNnFN | by the failure of the cap to explode; and that this is the chief cause of | the ayOidable class of misdres those that can be prevented by care on the part of the workmen In this paper therefore ! shall conhne my remarks chiefly 10 that part Of the subject
 The following definitions win be useful:
 To spit a fuse To ignite lt, a common miners term
 Flash.-The flashing of fire from the end Of the fuse, opposite 10 that at which it was spit
 Moderate mping.-Crimping with a moderately firm grasp of the hand, not hard enough to bend the handles of the crimpers.
 Hard crimping-Crimping as hard as the strength of the crimpers will permit.
 mishres that have come under my observation, where the fuse of primer was not cut of by the explosion of an adjacent hole, l have noticed that the fuse had burned as far down the hole as could be seen; and when the powder was exposed to view. it could be seen that the fuse had burned down into it. My courage and regard for my personal welfare was only occasionally equal to dig ging out tho powder to see if the cap had exploded. but l did this in certain favorable instances. and have had my foreman bring me unexploded leaps from missed holes when he found them In a missed hole of this kind. it is rarely that l have found the cap to have exploded. and lI have never found an unmutilated lpiece of fuse that had failed to burn to the end, even though it had been bent back in the primer. according to the questionable custom SO often lpractised by miners. Almost invaria- bly the fuse is found to have burned into the cap without exploding it. This fact puzzled me for a long time. but while the reason for the failure of the cap to explode connot always be known with certainty, it can often be explained as the result of carelessness, or wrong method of at- taching the cap, Three particular instances of this kind are fresh in my mind In one of these the cap had been orimped with the sharp point Of a knife, which bad been thrust so far into the side of the cap that ? lit bad penetrated to the train of powder ip the fuse, l should hardly