HIST363: Global Perspectives on Industrialization

Writings mention common risks to deep-vein miners and their observations of the effects. For example, Pliny writes, "when well shafts have been sunk deep, fumes of sulfur and alum rush up to meet the diggers and kill them" and "The fumes from silver mines are harmful to all animals". 3 issues were challenging in particular: ‍‍‍lack of lighting, poor ventilation and drainage.‍‍

Lighting

Figure 6: Hole for miner's lamp in an aqueduct

Figure 7: Typical Roman lamp

Without electricity, lighting was an issue for Roman miners. Aqueduct channels sometimes meandered from side to side‍‍‍‍; ‍‍‍‍‍we observed this during our aqueduct visit and learned that this was due to lack of light at that point in the dig. This is not always the case in mineral mines because the miner's goal is to follow the vein rather than try to follow a straight line. In order to hold lights in place and move forwards, miners dug small holes in the walls and used them to hold oil lamps similar to those found in Roman homes. ‍‍‍‍‍Pliny wrote that the candles were also used to measure a day's work, shifts completed when the candle's flame died. Although necessary, the use of fire had to be limited in the tunnels to not deprive the air of oxygen and suffocate workers.

Ventilation

Before entering a shaft, a lamp would be lowered into the tunnel to determine if the air was safe to breathe. If there was no oxygen, the flame would die out and additional shafts would be excavated on either side to improve air flow by convection. Galleries which met also helped improved air flow. A more risky method of increasing air flow was to set fires, but as mentioned before this had to be done carefully to not deplete oxygen levels. Workers could also wave linen cloths in the mines to increase air flow. Heat ‍‍‍‍worsened working conditions; for every 30 meters deeper, the temperature increased by 1 degree Celsius. In the case of the Paphlagonia mine along the Black Sea Coast, slaves were constantly replaced due to the poor ventilation. Diodorus notes that "there are more than 200 workers but they are continually consumed by sickness and death".

Drainage

Figure 8: Water table inside a tuff mine

The volume of leakage into a mine determined whether it would be usable or not. Miners who dug near the water table and subterranean rivers often found the infiltrating water to be too much and abandoned it. During my visit to a tuff mine‍‍‍‍, we saw for ourselves where the water table was. If the leakage was manageable, workers had methods of draining the water from the site including mechanical devices.

Drainage Audits

After the mine was excavated, small diversion channels called adits were dug which diverted water away from the work site. Similar to aqueducts, adits have a very slight slope that allows gravity to move water. If the miners were lucky, a naturally occurring hole nearby could act as a water tank and hold all or some of the drainage after excavating the adit. Before it was dug, water would have to be handled by other means.

Fireman Line

If the incoming leakage was relatively small, workers could form a fireman's line and bail out water from the mine. Bottoms of buckets were pointed so that the containers could be easily tipped and filled. Lifting them required a strong arm as they could hold up to 150 litres (150 kg) of water plus the weight of the metal container itself.

Mechanical Devices

To remove larger volumes of water, miners used mechanical devices powered by humans walking on pedals or turning cranks. The ‍‍‍‍‍‍‍‍Archimedean or Egyptian screw was constructed by fitting a metal augur with a crank at the receiving end inside a hollow wooden cylinder. The device worked by trapping small volumes of water between each vane and bringing them up. Multiple screws could be used in succession, lifting water as high as was necessary. Vitruvius specifies an optimal angle of 37 degrees to remove the maximum volume of water, about 35-40 gallons per minute. It is interesting to see the same type of augur used in today's construction industry to ‍‍‍‍remove soils from the ground‍‍‍‍.

Figure 9: Archimedean Screw

The water wheel was introduced not long after the augur screw. This system is similar to modern water wheels, except they were powered by workers who stepped on it like a staircase instead of with flowing water. Before the wheel could be used, a sump in the mines would have to be excavated to contain water and make space for the wheel. Rectangular containers along the wheel's circumference filled when they passed the bottom of the rotation and then emptied at the top, raising the water. Each wheel had to be designed with a diameter large enough to bring water up to the desired level, and were often used in series of pairs. At the ‍‍‍‍Rio Tinto‍‍‍‍‍, 8 pairs of wheels were found which raised the water a total of 30 meters.

Figure 10: Human powered water wheel

As each wheel rotates it creates turbulence, which makes it more difficult to catch water in the containers. To remedy this, each pair of wheels was situated so that they rotated in opposite directions. This counter-acted the turbulence of each wheel and improved efficiency. This was important because the sump had to be slightly sloped towards the wheel to return water to it, increasing the depth of each container dip and maximizing water removed per scoop.

Positioning the pairs of wheels like this reduced the slope needed and made construction easier. Wheels that have been recovered average "4-6 meters in diameter with 20-24 compartments". The advantage of the water wheel was that it could raise water higher, but at a slower rate than the Egyptian Screw. The performance of the wheel depended mostly on how far the buckets could be dipped into the water and where the water was emptied in the rotation.

Controlling turbulence and designing the wheel with the right diameter were important considerations when using this machine. Drainage was arguably the most challenging problem for Roman miners as all removal processes required a large amount of resources and was not guaranteed to work.