Short answers, pulled from the story.
Friedrich Engels walked the streets of Salford and Manchester between 1842 and 1844. He compiled detailed contemporary reports alongside his own observations during this specific timeframe.
Before the introduction of mills between 1779 and 1787, 4,408 out of 10,000 children died before age five. After the mills arrived, that number rose to 4,738. Mortality from convulsions reached ten times the rural average.
Karl Marx read Engels' manuscript after their second meeting in 1844. The encounter took place in Paris during that same year.
An American named Florence Kelley Wischnewetzky translated the book into English in 1885. The English version published in New York appeared in 1887 with a London edition following in 1891.
The overall death rate in Manchester stood at one person for every 32.72 residents while Liverpool recorded a figure of one in 31.90. The national average sat at one death per 45 or 46 people.