It is noticed that labourers employed in deep mines worked by shafts suffer less from fever than do those who are engaged in stripping the alluvial deposits.
The shafts are placed so close together that in many instances they are divided by only a couple of feet of solid ground, but at their bases a considerable amount of gallery work has been excavated, though it is possible that this was done by miners who came after the people who originally sank the shafts.
In cases where the direction of the air motion is always the same, as in the ventilating shafts of mines and buildings for instance, these anemometers, known, however, as air meters, are employed, and give most satisfactory results.
Each coil is attached to a shaft by a bell crank arrangement, and to these shafts there is secured a system of levers similar to that at the transmitter carrying the receiving pencil at the junction.
The shafts are turned by the pull of the magnet upon the coils, and the motions of the transmitting pencil are thus reproduced.
They consist of seven different levels, one above the other, and have eleven shafts, two of which are in the town.
Except at the shafts, which were sunk on proposed station sites, there was no interference with the surface of the streets or with street traffic during construction.
Striking the shafts of the Comstock Lode, securing ventilation and cool air for the miners, draining the mines above its level, and obviating much pumping and hoisting.'
By way of reprisals for the Hussite outrages in Prague, the miners of Kuttenberg seized on any Hussites they could find, and burned, beheaded or threw them alive into the shafts of disused mines.
The piers carrying the arches have shafts at their angles, the earliest examples known, and the decoration of the walls consists of friezes, borders, and impost-bands, all enriched with conventional patterns interwoven with cufic characters and modelled in stucco.
Light and air are introduced by means of vertical shafts (luminaria) running up to the outer air, and often serving for several storeys.
No shafts or tunnels are necessary except for exploration; the mining consists entirely in open-cut and terrace work.
In working downwards in open quarries and in tortuous shafts and passages much of the mica is damaged, and a large amount of labour is expended in hauling waste material to the surface.
According to some, Niobe is the goddess of snow and winter, whose children, slain by Apollo and Artemis, symbolize the ice and snow melted by the sun in spring; according to others, she is an earth-goddess, whose progeny - vegetation and the fruits of the soil - is dried up and slain every summer by the shafts of the sun-god.
Large beds of rock-salt also occur in the neighbourhood, in which shafts have been sunk to a depth of more than 1200 ft.
The bases of the columns are either reeded or decorated with a plait-pattern; the capital has the broad channel between the volutes subdivided by a carefully-profiled incision; and the top of the shafts is ornamented by a broad band of palmette or honeysuckle pattern.
The shafts reached deposits of salt at a depth of 850 ft., but the finer and purer layers lie more than 1 roo ft.
As the sinking of shafts or the driving of narrow entries or drifts is expensive, and as the mineral extracted rarely pays more than a small fraction of the cost, it is usual to plan this exploratory work so that the openings made shall serve some useful purpose later.
The mistake is often made of sinking large and expensive shafts, or driving costly tunnels, before it is fully proved that the deposit can be worked on a scale to warrant such developments, and, indeed, too often before it is known that the deposit can be worked at all; and in too many cases large amounts of money are thus unnecessarily lost by over-sanguine mine managers.
They are to be preferred also for very deep shafts, or for sinking in difficult ground.
Drifts and inclined shafts following the deposit may prove difficult of maintenance when the workings become large and settlement of the overlying strata begins.
Large pillars of mineral should be left for the protection of the main openings, whether these be shafts or adits.
I and 2 illustrate the development of a metal-vein by two adits, two inclined shafts in the lode, and by a deep vertical shaft connected with the lode by horizontal cross cuts.
As already noted large pillars must always be left to protect shafts, adits and the more important mine-passages necessary for drainage, ventilation and the haulage of mineral.
Of inclined shafts, from which long horizontal rooms branch off right and left.
The size, shape and design of the cars depend on the size of the mine passage and of the hoisting compartments of the shafts; on whether the cars are to be trammed by hand or hauled in trains; whether they are loaded by shovel or by gravity from a chute; and whether they are to be hoisted to the surface or used only for underground transport.
Near the top and bottom of hoisting shafts the tracks are usually graded to permit the cars to be run to and from the shaft by gravity.
When the mine is worked through shafts, hoisting plant must be installed for raising the ore and handling men and supplies.
On a smaller scale hoisting is also necessary for sinking shafts and winzes and for various underground services.
In deep shafts hoisting speeds of 3000 or 3500 ft.
A frame of wood or steel, erected at the shaft mouth, and rarely employed except for deep shafts of small cross-section or when the mine cars (tubs) are small, as in many parts of Europe.
Skips are sometimes of very large capacity, holding 5, 7, and even 10 tons of ore; such are used, for example, in several shafts at Butte, Montana, in the Lake Superior copper district, and in South Africa.
Shafts in South Africa, the United States and elsewhere, are already approximating depths of 5000 ft., a few being even deeper.
At mines with vertical shafts this is a simple operation.
These are common in Europe, and are sometimes employed in the United States and elsewhere in mines where the output is large and the shafts deep and of small cross section.
At a few mines special man-cages are operated in separate compartments by their own engines for handling part of the men, and for tools, supplies, &c. For inclined shafts, where the mineral is hoisted in skips, the operation of raising and lowering men may not be so simple.
When the shafts are deep and the number of miners large man-cars are sometimes employed.
Such cars are in use at a number of deep inclined shafts in the Lake Superior copper district, where the depths range from 3000 to 5000 ft.
(2) For raising large volumes of water from deep shafts pairs of tanks are operated in balance in special shaft compartments by their own hoisting engine.
Sinking pumps, designed for use in shafts in process of sinking, are suspended by wire ropes so as to be raised before blasting and promptly lowered again to resume pumping.
In a mine with shafts opening at the same level, natural ventilation once established will be effective during cold weather, as the downcast will have the temperature of the outside air, while the upcast will be filled with the warm air of the mine.
In a mine with two shafts a ventilating current may result from other conditions creating a difference in the temperature of the air in either shaft - for example, the cooling effect of dropping water or the heating effect of steam pipes.
Three other shafts of the Tamarack Company, and three of the neighbouring Calumet and Hecla mine, have depths of between 4000 and 5000 ft.
Deep. In Austria three shafts in the silver mines at Prizbram have reached the depth of over 1000 metres.
At Bendigo in Australia are several shafts between 3000 and 4000, and one, the Victoria Quartz mine, 43 00 ft.
Deep. In the Transvaal gold region (South Africa), a number of shafts have been sunk to strike the reef at about 4000 ft.
Shafts 20 or 30 ft.
It lies in a valley between the hills of Birkenberg and Heiliger Berg, and in its neighbourhood are the lead and silver mines which belong to the Austrian government and are worked in nine shafts, two of which, the Adalbert shaft (3637 ft.) and the Maria shaft, (3575 ft.) are the deepest in the world.
In alluvial deposits the richest ground is usually found in contact with the "bed rock"; and, when the overlying cover of gravel is very thick, or, as sometimes happens, when the older gravel is covered with a flow of basalt, regular mining by shafts and levels, as in what are known as tunnel-claims, may be required to reach the auriferous ground.
Side of the hill on which stands the village schoolhouse, from which one looks across the indentation to the Apollo temple, several vertical shafts in the limestone stratum were found, and underneath it in horizontal passages were bodies surrounded with vases.
Broad; it has vertical shafts at intervals, and a sluice chamber at its egress from the lake.
(For the methods of boring see Boring.) The working of coal may be conducted either by means of levels or galleries driven from the outcrop in a valley, or by shafts or pits sunk from the surface.
The mode of winning by level is of less general application than that by shafts, as the capacity for production is less, owing to the smaller size of roadways by which the coal must be brought to the surface, levels of large section being expensive and difficult to keep open when the mine has been for some time at work.
Shafts, on the other hand, may be made of almost any capacity, owing to the high speed in drawing which is attainable with proper mechanism, and allow of the use of more perfect arrangements at the surface than can usually be adopted at the mouth of a level on a hill-side.
The sinking of colliery shafts, however, differs considerably from that of other mines, owing to their generally large size, and the difficulties nkingof g g y g ?
The size and form of colliery shafts vary in different districts.
Poetsch in 1883, and originally applied to shafts passing through quicksands above brown coal seams, has been applied with advantage in opening new pits through the secondary and tertiary strata above the coal measures in the north of France and Belgium, some of the most successful examples being those at Lens, Anzin and Vicq, in the north of France basin.
In an application of this method at Vicq, two shafts of 12 and 16.4 ft.
The side horses, pressing against the shafts of the middle horse, sank in the snow, which was dry and glittered like sugar, and threw it up.
"That time I'd harnessed two young side horses with the bay in the shafts," he went on, turning to Dolokhov.
Ten shafts lined with slabs of tufa which were there found may have been the approaches to tombs or may have served as wells.
Air-shafts, or luminaria.
Vertical shafts are better adapted to rapid hoisting, and have therefore somewhat greater capacity, than inclined shafts.
As soon as it appears reasonably certain that the property is workable the mine will be opened by one or more shafts, drifts or tunnels, and the underground passages for active mining operations will be started.