On the whole, the quote that started this thread is correct. However, I don't find anywhere that Russell stated that he had never seen the Herald of the Morning, or was not acquainted with Barbour. This is going beyond what is written. Russell had heard the 1873 time proofs from Wendell, and might have heard or read of Barbour, since he had also used the same proofs. It is true that Barbour had a magazine called "The Midnight Cry" that had a circulation of 15,000. But after the disappointment of 1873, the circulation fell, and a magazine with a new title "Herald of the Morning" was started. But the following was small. Although Russell seemed to have known about the disappointment of 1873, it seems from his account, that he was not aware of the movement's activities, or change of beliefs. He does not tell how the magazine came to him.
But there are questions that remain about this. What was the connection between that Bible study class that Russell started, and that Advent Christian church of which Wendell was pastor? How did Russell hear about the time proofs from Wendell? How can one unlearn errors without learning truth at the same time? If Russell was not an Adventist, why were his associates Adventists? Barbour, Paton, Wendell, Stetson were all preachers of the Advent Christian Church, and Storrs had been a leading preacher under William Miller. Did he lie about not being an Adventist?
I don't think he was lying, for one reason because he acknowledges that he was previously familiar with those time proofs of the Second Adventists, and their beliefs that he disagreed with. And the statement that he made that he learned no single truth from the Adventists, but they helped him unlearned errors, and prepare him for the truth - that statement is contradictory. He could have been deceiving himself about the matter.
There is some ambiguity of meaning to the word "Adventist." It can refer to anything coming out of the William Miller movement. But "Second Adventist" refers to someone belonging to the Advent Christian Church, which at the time was the largest Adventist group. The ACC organized, and the term "Second Adventist" was a denominational label. But many Adventists, like Storrs and others, were opposed to organization and denominations, and rejected therefore the label "Adventist" and would not call themselves an Adventist. They thought denominations were "Babylon", which they had left. There were other Adventists who were called "Age-to-Come" Adventists. They did not believe in the burning in the world, and believed in a literal kingdom on earth, and some believed in a future probation. Wendell was not an Age-to-Come Adventist, but Storrs and Stetson were. Russell as early as 1869 held to this view. He does not tell how he arrived at this view so early after being an agnostic, and regaining his faith in the Bible. My guess is that, since Wendell did not teach this, then he met someone at the Adventist church that steered him in that direction, perhaps this was Conley, who was in Russell's bible class.
The Age-to-Come Adventists and the Advent Christians would fellowship with each other at that time. They become more organized and separate later on. But the Age-to-Come Adventists were adverse to organization, and they commonly called themselves "The Church of God." Many of the Age-to-Come Adventists later organized as the "Church of God of the Abrahamic Faith." I have their history booklet, called Historical Waymarks of the Church of God. It shows that in the earlier years before 1900, Advent Christians and their believers met in the same church together, more commonly in the Midwest and West.
I have seen the original paper of the Advent Christian Church, called the World's Crisis and Advent Christian Times. There, in the 1870s, that Allegheny church is advertised as "The Church of God." This might indicate that there were a number of Age-to-Come believers in that church, including Stetson, who was pastor for a while. It is possible that Russell's Bible study class was actually a minority subgroup within that church. So Russell might have regularly attended the meetings of that Advent Christian Church, and heard Wendell and Stetson preach there, and attended his own class on Sunday evening, and yet since he disagreed with some fundamental beliefs of the Advent Christian Church, could in good conscience deny that he was an Adventist.
However, he does downplay his connection with the Adventists, and does not state Stetson and Storr's connections with the Adventists. Russell was definitely acquainted with the Adventist literature, quoting their articles in the Watch Tower even through the 1880s. In the Advent Christian papers, in the early 1870s, Russell's name appears frequently, not as writer of articles, but acknowledging receipt of his correspondence. I am assuming that he requested literature from them and gave money. So Russell knew about these papers at that time. Barbour's articles on 1873 appear in the Adventist papers, and Russell could have read them at the time.
As far as what this tells us, history shows that date-setting leads to disappointment. Storrs, Barbour, Wendell - each set dates, and experienced disappointment. The Three Worlds expected that the rapture would occur in 1878. We can see that this was a mistake. Storrs advised Russell and Barbour against date-setting. Storrs learned his lesson through experience, which Russell did not have, he was a young man. Russell made a mistake in following Barbour, and not listening to his former mentor.
Steve