Princess mine explosion

The first significant explosion in a Cape Breton coal mine took place in 1878 in the “Sydney mines,” what would later be called the Princess mine.

Historical accidents are a key reason why the modern mining industry is so safety-focussed. Nova Scotia’s mining and quarrying industry has reduced its injury rate by 90% since the Westray inquiry report was released in 1997. We believe the most important thing to come out of a mine is the miner, and our modern safety record reflects this.

However, coal mining was often a dangerous job historically, often due to methane, a gas formed as organic matter decomposes in the absence of oxygen, such as when plants die in wetlands, marshes and swamps – the sorts of places where coal usually forms. The methane is trapped in the coal as it forms and is released as coal is mined. Methane is combustible, so underground coal mines use ventilation systems to vent methane and prevent it from pooling and triggering fires and explosions. Unfortunately, historical safety practices and equipment were often insufficient, and accidents often occurred.

Edwin Gilpin, Nova Scotia’s Deputy Commissioner and Inspector of Mines, presented a paper about coal mine explosions to the Federated Institution of Mining Engineers’ annual general meeting in 1894.

Gilpin told the attendees that “official records of coal-mining in Cape Breton go back to the year 1785... During this long period, the deepest shaft and workings have equalled a vertical depth of 700 feet. Gas has seldom been met in quantities large enough to cause trouble.” He said various factors in the Cape Breton mines, such as dampness, “appear to have resulted in an almost complete discharge of gas from the seams as far as they have been worked.”

In other words, while there had been relatively minor ignitions of methane in Cape Breton mines, their rudimentary ventilation and natural factors had prevented large explosions.

The one significant exception, Gilpin said, was an explosion in the “Sydney mines,” which is what the coal mines in the area were originally called. Sydney Mines was incorporated as a town in 1889 and the area was referred to as “the Mines” prior to that.

What later came to be known as the Princess mine was the first to extract undersea coal in the Sydney Coalfield. Its main shaft was near the shore and the workings were entirely under the ocean.

The shaft was started in 1868 but due to issues with water leaks, the seam was not reached until 1876. The shaft had to be lined with metal through 300 feet of water-bearing rock to ensure safety, a significant engineering achievement at the time.

On Tuesday, May 21, 1878, the mine’s under manager, Isaac Greenwell, and an overman, William Oram, entered an area of the mine that had been idle for some time. Their purpose was to plan the resumption of mining in the area.

While they were underground, according to the 1878 Department of Mines annual report, “a blast of air and dust up the unfinished winding shaft intimated only too plainly that some serious explosion had occurred in the workings. The agent, with some volunteers, immediately hastened below to render assistance to the imprisoned men and supervise the work of restoring the ventilation in the absence of the under manager and overman, who were among the missing.”

The explosion was confined to the deeps on the north side of the mine. Some men on the south side continued to work, unaware that an explosion had occurred.

A group of men were found alive, trapped by the explosion’s after damp (carbon monoxide) that was between them and the bottom of the mine’s shaft. One man, Robert Hutcheson, had tried to get through the after damp but was overcome and died. The group tried to rush through the after damp as the rescuers approached, some making it while others fell to the ground from its effects. The rescuers put their own lives at risk to help those who had fallen.

The bodies of Greenwell and Oram were found about 60 feet from the mine’s working face and were, according to Gilpin, “not much burned.” The coal near them had not been “coked” (burned at high temperatures), and the roof supports had not been disturbed. However, in a lower tunnel, “there was evidence of great heat and violence.”

An investigation of the explosion found that Greenwell and Oram had accidentally ignited methane in an upper tunnel and it flamed into methane in a lower tunnel, carrying coal dust and air with it, causing a severe explosion.

They had carried “naked lights,” devices with open flame so they could see, despite the fact that the area was not being inspected daily for safety issues, such as methane, since it was inactive.

It was later described as “incomprehensible” that they used naked lights in such circumstances, in direct contravention of safety rules. However, the Department of Mines annual report suggested, “it is possible that the under manager did, or intended to, try all suspicious places with his candle, for he prided himself on the steadiness of his hand, and he alone carried a candle.” (Methane burns with a blue flame so inspecting for it was done by monitoring its effects on a hand-held flame, a practice that is obviously risky since flame can also ignite larger quantities of methane.)

Because the area had not been worked recently, a brattice (canvass door) that usually covered the entrance to one of the tunnels to guide air flow had been taken to another part of the mine. This affected ventilation and likely allowed methane to pool in the area. According to the annual report, “there was no evidence to show that [the under manager] had ordered the replacing of the door, which, for a man so generally careful, it is probable that he thought he had done, even if he failed to give the order….”

A total of six men were killed in the explosion and its after damp.

After the incident, the mine’s operator, the General Mining Association, installed a Guibal fan, the first mechanical ventilation fan at a Cape Breton mine. The Guibal fan was patented in Belgium in 1862 by French engineer, Théophile Guibal. It had a spiral case surrounding the fan blades, as well as a flexible shutter to control the escape velocity, which made it far superior to previous open-fan designs and led to the possibility of mining at great depths.

Fans became standard in underground coal mines because of the importance of ensuring proper ventilation. Powerful fans are used to draw air through mines, bringing fresh air in from surface and eventually expelling air and any methane back at surface. Fans inside mines also often help move air along. Devices like brattice and doors are used to control where air flows, to increase circulation where mining activity is taking place and where methane risks pooling.

The Princess mine closed in 1975 after a century of work. Learn more about it at