I often see drill holes in rocks along the trail while hiking and I assume they were put there either for purposes of geological sampling or as part of the trail building process. I have also wondered what kind of machinery was used to drill them. Wandering around the web I see that there is a process called 'single jack drilling' and for history buffs, what used to be hard manual labor has become recreation:
Contestants use 4½ pound hammers and as many as 11 bits of graduated steel to drill a ¾ inch hole in a 4,320 pound piece of Sierra White Granite.
The contestants have 10 minutes to pound the drills into the solid stone, their only help from an assistant who runs water into the hole so the loose stone chips are splashed out with every stroke of the hammer on steel. The deepest hole wins.
The world record was set in 1993 at 16.34 inches deep by Scott Havens of Elko, Nevada.
Do any of you history buffs here at NWHIKERS know of any museums in Pugetopolis where some of this equipment might be seen??
Miners would call those holes "glory holes." In the 20th century that term took on a whole new meaning. If you are ever in Juneau AK you can have a drink at the Glory Hole tavern. With every charge of dynamite placed into the hole the miner had dreams of "glory" with gold being found hence the name.
According to a RR buff I know, the "drills" consisted of a star bit, shaft, and striking head. By adding (threading on) additional shafts, a person could theoretically drill for several feet. The depth of a single bore was limited more by the rock's resistance to the charge. Shaft sections of varying lengths could be used as the bore progressed to keep the swing arc from becoming awkward. This accommodation had more to do with production than it did ergonomics.
Prior to widespread use of compressed air, small demolition and pavement breaking jobs employed hand gads and sledge hammers. This two-man operation started out with one man holding the gad and a second worker striking the head of the gad. After the gad was sufficiently embedded -- generally in a brick surface -- both workers alternated swings at the gad. Tongs were sometimes used by the guy holding the gad for obvious reasons.
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