 They were the first in Ontario to sink a shaft to below 4,000 feet.Ennis established mine safety procedures, including a daily report on safety conditions underground, a standard that is common today, and an attempt to tackle the serious health problem of silicosis.At the time, European researchers had hypothesized that the scarring of lungs caused by silicosis was the result of a complex chemical reaction between silica particles and lung tissue, although this is now known to be inaccurate.