"Hitherto It Is Questionable If All the Mechanical Inventions Yet Made Have Lightened the Day's Toil of Any Human Being" Context Blogging
In the Ashley edition that has been standard since... 1909, I believe, the end of Book IV, Chapter 6, "Of the Stationary State" of John Stuart Mill's Principles of Political Economy with Some of Their Applications to Social Philosophy reads:
Of the Stationary State: Hitherto  it is questionable if all the mechanical inventions yet made have lightened the day's toil of any human being. They have enabled a greater population to live the same life of drudgery and imprisonment, and an increased number of manufacturers and others to make fortunes. They have increased the comforts of the middle classes. But they have not yet begun to effect those great changes in human destiny, which it is in their nature and in their futurity to accomplish. Only when, in addition to just institutions, the increase of mankind shall be under the deliberate guidance of judicious foresight, can the conquests made from the powers of nature by the intellect and energy of scientific discoverers, become the common property of the species, and the means of improving and elevating the universal lot.
The "" in square brackets was added by W.J. Ashley in 1909 to indicate that that that first sentence, with its "Hitherto," had been in the book since its first 1848 edition. Mill's time references, Ashley explained, were:
occasionally a little bewildering: a "now" in his text may mean any time between 1848 and 1871. In every case where it seemed necessary to ascertain and to remind the reader of the time when a particular sentence was written, I have inserted the date in the text in square brackets...
Political Economy came out in seven editions: 1848, 1849, 1852, 1857, 1862, 1865, and 1871. In none of them did Mill himself think that it was worth changing "hitherto" to "formerly."