Either by accident or design Russell actually changed one of Smyth's measurements from 3461 inches to 3416 inches when he used it to calculate the date 1874 for the "beginning of the period of trouble". When 'The End' failed to materialise Russell changed the measurement in 1910 to 3457 inches and announced a new date of 1914. Not only had Russell now corrected his transposition of earlier he also removed four inches from Smyth's measurements in order to back up his revised chronology.The above appears to be referring to the change Russell made to his third volume in 1905 (not 1910). If so, this change was pertaining to only the floor of the lower part of the descending passageway. It was not a change to Smythe's measurement, since Smythe was unable to measure that lower part due to debris; the attempt was to take Smythe's measure of the ceiling of the passageway and try to project it to the floor. Thus there was already some uncertainty concerning the measurement. Nevertheless, evidently the original projection to the floor of the lower passageway was done by Nelson Barbour.
The details surrounding how the change took place in 1905 is not presented in any records I have been able to find. Evidently, Russell or one of his associates began to question the measurement provided, and a new projection was made, This had nothing to do, however, with any alleged failure of "the end", whatever that is supposed to mean. Nor did the change in the third volume announce a new date. 1914 had already been viewed by many Christians as being the end of the Gentile Times based in Bible prophecies. As best as I can determine, the first person to present 1914 as possible end of the times of the Gentiles was E. B. Elliott in 1844. Russell accepted this believe in 1876, and he announced his acceptance of that date in that same year. Russell presented several lines of Biblical proofs of that date in his second and third volumes of this Studies in the Scriptures. Thus, the change in the third volume in 1905 did not create "a new date", and most definitely the change was not because "the end failed to materialise", whatever that is supposed to mean.
I have more regarding this change on my website:
http://rlctr.blogspot.com/2017/01/changes-gp.html
Russell spent his life and his fortune defending the basic teaching of the atonement by means of Jesus Christ.