What is the difference between: in 1870 he had set up and in 1870 he set up? -- The writer simply wishes to make it clear that the set-up of his laboratory had been completed when he decided to become an inventor. It is a look back into the past of the past because Edison's conflict with Jay Gould came between the lab set-up and the status of independent inventor; the lab set-up is not the thrust of the statement, and the dates are for historical interest (an historian will throw in more dates than writers in other fields, of course).
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