Английская Википедия:Dredge No. 4
Шаблон:About Шаблон:Use Canadian English Шаблон:Short description Шаблон:Infobox machine
Dredge No. 4 is a wooden-hulled bucketline sluice dredge that mined placer gold on the Yukon River from 1913 until 1959. It is now located along Bonanza Creek Road Шаблон:Convert south of the Klondike HighwayШаблон:Sfn near Dawson City, Yukon, where it is preserved as one of the National Historic Sites of Canada. It is the largest wooden-hulled dredge in North America.Шаблон:Sfn
With its 72 large buckets, the dredge excavated gravel at the rate of 22 buckets per minute, processing Шаблон:Convert of material per day. It was in use from late April or early May until late November each season, and sometimes throughout winter. During its operational lifetime, it captured nine tons of gold.
Background
About Шаблон:Convert south of the dredge's current site, further into the Klondike Valley, is the Discovery ClaimШаблон:Sfn where gold was found in August 1896 by prospector George Carmack, his Tagish wife Kate, her brother Skookum Jim, and their nephew Dawson Charlie.Шаблон:Sfn This is considered the site where the Klondike Gold Rush began.Шаблон:Sfn
Integral to the operation of the dredge were the services available at Dawson City.Шаблон:Sfn There, financial services provided by the banks, administrative services provided by the Government of Canada, and the rail and steamship transportation network terminating at the city ensured that machinery needed for operation of the dredge would be readily supplied.Шаблон:Sfn
The Canadian Klondyke Mining Company built the Twelve Mile ditch in 1909, which would supply the water to operate hydraulic monitors on dredges.Шаблон:Sfn It also built dams and ditches to generate hydroelectricity, and by 1911 the Шаблон:Convert North Fork Hydro Power Plant was operational about Шаблон:Convert from the dredges it energized.Шаблон:SfnШаблон:SfnШаблон:Sfn
History
Designed by the Marion Steam Shovel Company, the bucketline sluice dredgeШаблон:Sfn was built on site at Claim 112 Below Discovery from mid 1912 until the onset of winter.Шаблон:Sfn The assembly site was near Ogilvie Bridge, named for William Ogilvie, near the current location of the bridge carrying the Klondike Highway to Dawson City.Шаблон:SfnШаблон:Sfn Construction was supervised by Howard Brenner, an engineer employed by the Marion Steam Shovel Company, who also supervised construction of Dredge No. 3 at the same time.Шаблон:Sfn A contract for the parts dated 13 March 1912 specified their shipment to the site in the summer of 1912, at a cost of $134,800 for each dredge, and the hull was built by the Canadian Klondike Mining Company.Шаблон:Sfn
The Canadian Klondyke Mining Company began operating the dredge in May 1913.Шаблон:Sfn After eleven years of operation, it had cut its way to the Boyle Concession, where it sank in 1924.Шаблон:Sfn By 1927, it had been refloated and worked its way to Hunker Creek, where it could produce up to Шаблон:Convert of gold a day at claim 67 Below Discovery.Шаблон:Sfn It ceased operations in the area on 11 July 1940, and was rebuilt by the Yukon Consolidated Gold Corporation on Bonanza Creek, where it resumed operations on 11 September 1941.Шаблон:Sfn The wooden hull of the original dredge was discarded, left in the pond where it sank, but all other parts were salvaged for use in the reconstructed dredge.Шаблон:Sfn It worked its way downstream on one side of the valley, then back up the other side, until being decommissioned on 1 November 1959.Шаблон:Sfn
The immediate success of the dredge resulted in the Canadian Klondyke Mining Company ordering the construction of two more dredges the following year.Шаблон:Sfn
Operation
The electrically-powered machine required Шаблон:Convert while digging, and more when moving its gangplank.Шаблон:Sfn With its installed hydraulic monitors, the eight-storey dredge would cut into gravel banks, washing down the released material for processing.Шаблон:Sfn The machine created a dredge pond by virtue of its operation, its size dependent on the valley in which it was operating, but sometimes reaching Шаблон:Convert.Шаблон:Sfn It would rotate on two spuds, each Шаблон:Convert and Шаблон:Convert long.Шаблон:Sfn
The Шаблон:Convert digging ladder enabled the dredge to dig a cut with an average arc of about Шаблон:Convert.Шаблон:Sfn This wide arc was possible because of the use of two spuds.Шаблон:Sfn It could reach Шаблон:Convert above water level and Шаблон:Convert below it, with each of the 72 buckets capable of moving loads up to Шаблон:Convert.Шаблон:Sfn Each bucket weighed Шаблон:Convert, each flange Шаблон:Convert, and each securing pin Шаблон:Convert.Шаблон:Sfn
Gold was recovered in a rotating Шаблон:Convert long trommel screen with Шаблон:Convert diameter and 12.5% grade.Шаблон:Sfn A pipe was suspended within the trommel, carrying water upwards to spray the incoming material, cleaning it and breaking up larger lumps.Шаблон:Sfn Finer material (gold, sand, and pebbles) was sieved through Шаблон:Convert holes in the screen, which rotated at 7.8 revolutions per minute, into a distributor box.Шаблон:Sfn From there, it flowed into sluice tables, long troughs with an area of Шаблон:Convert which had a constant flow of water.Шаблон:SfnШаблон:Sfn About 75% of the gold was caught in a Шаблон:Convert coconut matting and steel riffles at the bottom of the troughs.Шаблон:Sfn A smaller distributor captured another 20% of the gold, and all remaining material was washed out into the dredge pond.Шаблон:Sfn The larger pieces of gravel were ejected from a Шаблон:Convert wide stacker at its rear, a Шаблон:Convert belt moving at Шаблон:Convert.Шаблон:Sfn These tailings remain as a "vast, rippled blight on the landscape".Шаблон:Sfn Particles of gold and nuggets too large to fit through the screen holes would be ejected with the gravel.Шаблон:Sfn
In its 46 years of operations, the machine mined nine tons of gold, dredging 22 buckets of gravel every minute,Шаблон:Sfn about Шаблон:Convert per day.Шаблон:Sfn Dredge No. 4 had a much greater capacity than other dredges that were operating in the area, and could sometimes operate through winter. In 1918, it began operating on 1 May, and continued until 3 April 1919, at which time it was stopped for repairs.Шаблон:Sfn
It worked without interruption from late April or early May until late November every year.Шаблон:Sfn At the end of each season, the buckets were removed.Шаблон:Sfn More than twenty dredges operated throughout the same area, with the first built in 1899.Шаблон:Sfn
Crew
The crew who operated the dredge consisted of various positions. The dredge master was responsible for ensuring the productivity of the dredge, and would also serve as winter watchman.Шаблон:Sfn Among the position's activities were documenting crew hours and breakdowns, and preparing a dredging plan for the area to be excavated.Шаблон:Sfn The winchman operated the dredge from the master control room, taking over for the dredge master on the evening and night shifts.Шаблон:Sfn Among the winchman's tasks were supervising the crew and operating the digging ladder.Шаблон:Sfn An oiler lubricated and maintained all moving parts, including pumps, motors, tumblers, and the main drive, and replaced worn parts, also substituting for the winchman at times.Шаблон:Sfn
The bow decker was responsible for the bucket line, cleaning clay away from the lip of each bucket as it passed along the digging ladder, inspected buckets and pins for damage, cracked large rocks in the buckets with a sledgehammer, removed root and log debris from the buckets, and cleaned the deck.Шаблон:Sfn A stern decker was responsible for the stacker,Шаблон:Sfn ensuring it did not interfere with the power lines, that it remained clear of the tailings, and that any debris that jammed the conveyor belt was cleared.Шаблон:Sfn Large dredges, such as Dredge No. 4, also employed a panner, who obtained samples of material from the bucket line to inspect its colour.Шаблон:Sfn
The lowest-ranking group was known as the "bull gang", three to five members who were responsible for the machine's cables, the incoming power lines, and the "deadmen".Шаблон:Sfn The latter were two bulldozers along the shore of the dredge pond, attached to the dredge by steel cables, and were used as anchors.Шаблон:Sfn
National Historic Site
The dredge lay dormant where it was decommissioned from 1959.Шаблон:Sfn In the spring of 1960, a dam collapse flooded the creek in which it lay, rotating it 180° and lifting it off the shelf on which it was resting.Шаблон:Sfn It was purchased by Parks Canada in 1970 for $1,Шаблон:SfnШаблон:Sfn to become part of its proposed commemoration program for the Klondike goldfields.Шаблон:Sfn It was not until 1991 that it was excavated, and in 1992 it was moved to its current site, where it is protected from seasonal flooding.Шаблон:Sfn
On 22 September 1997, Dredge No. 4 was designated a National Historic Site of Canada because of its association with Klondike gold mining and as symbolic of the evolution of gold mining from a labour-intensive activity to a mechanical process.Шаблон:Sfn It is one of five National Historic Sites in the Dawson City area, the others being the Шаблон:SS and the Dawson Historical Complex.,Шаблон:Sfn Discovery Claim National Historic Site and the Former Territorial Courthouse. In 2012, Parks Canada reduced its budget, eliminating 600 jobs and stating that historic sites with low visitation would be accessible only on self-guided tours instead of being led by a guide.Шаблон:Sfn Among them was Dredge No. 4.Шаблон:Sfn Today, a private company provides guided tours of the dredge.Шаблон:Sfn
Notes
References
- Шаблон:Cite book
- Шаблон:Cite news
- Шаблон:Cite news
- Шаблон:Cite web
- Шаблон:Cite thesis
- Шаблон:Cite news
- Шаблон:Cite journal
- Шаблон:Cite book
- Шаблон:Cite web
- Шаблон:Cite encyclopedia
- Шаблон:Cite web
- Шаблон:Cite web
- Шаблон:Cite web
Further reading
External links
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