This graph illustrates the extent of one specific activity of the Toronto working class in these years. Strikes were most often used to demand wage increases, to resist wage reductions and to exercise control over the work process. The gap in the graph is unfortunate but the data is not available for the years 1892-1900.
If you compare the peak years of strike activity to the essay's discussion of business cycles it will become apparent that strikes coincided with prosperous times. It was only when the workers' own commodity, his labour power, was in demand that he had the strength to struggle with the employer. The peaks in 1872, 1881-1882 and 1886-1887 were all associated with mass struggles on the part of Toronto workers.