How unique were Russell's original teachings? Were they based solely on the Bible? Or did he receive influence from several other sources? What do you think?
Personally, I think Russell did a pretty good job of telling us some of his sources. Let us consult, first of all, Zion's Watch Tower (May 1890) under the heading "Harvest Gatherings and Siftings. A Brief History of the Development of Present Truth." He starts his narrative with 1868 when he happened upon Jonas Wendell and the Second Adventists. "Though his Scripture exposition was not entirely clear, and though it was very far from what we rejoice in, it was sufficient, under, God, to re-establish my wavering faith in the divine inspiration of the Bible, and to show that the records of the apostles and prophets are indisolubly linked. What I heard sent me to the Bible to study with more zeal and care than ever before, and I shall ever thank the Lord for that leading; for though Adventism helped me to no single truth, it did help me greatly in the unlearning of errors, and thus prepared me for the truth..." "At this time, myself and a few other truth seekers in Pittsburgh and Allegheny formed a class for Bible study..." But were most members of this original Bible class Bible Students? Not according to Russell in Z.W.T. Feb. 1881, R. 187: page 3 under "Cast Not Away Therefore Your Confidence." See "A Glance Backward" where Russell admits "Looking back to 1871, we see that many of our company were what are known as Second Adventists..." (They should not to be confused with Seventh Day Adventists.) If they became Bible Students it was much later as we shall see. But Russell himself never admits to being a Second Adventist at all. The very same article credits Second Adventist Benjamin W. Keith with finding that the Emphatic Diaglott translated Matt. 24: 37 and 39 as "presence" rather than "coming." These Adventists had been expecting Christ to return bodily in the fall of 1874, but they were disappointed when it didn't happen. That sent them back to the drawing board. Keith, a contributor to the Second Adventist magazine, Herald of the Morning made the discovery that Christ had indeed come in 1874, not physically but invisibly. He shared his find with the editor, N.H. Barbour. The Second Adventists could now say that they had the right date (1874) but had just expected the wrong thing to occur.: So, the invisible presence of Christ is not original to Russell. And while he may have denied that Adventists helped him to no single truth, his own writings contradict it. See ZWT (July 15, 1906 issue) wherein Russell explains how he came to be associated with Barbour in 1876 and how he adopted Barbour's chronology as well. He had not up to this point been interested in the subject of prophetic time. Russell ends up being assistant editor, along with J.H. Paton of Barbour's Second Adventist magazine, the Herald of the Morning. It is also this magazine (not the Watch Tower) which first indicates that the "Times of the Gentiles" would end in 1914. This date, too, Russell adopted from the Second Adventists.
In the following article in ZWT (Oct.-Nov. 1881), page 3, entitled "And the Door was Shut" Russell expresses what he thought of both William Miller and Barbour. "To return to the parable. If these movements were of God, and if Brothers Miller and B-----were his instruments, then that 'Midnight Cry,' based on the prophetic and other statements and evidences, was correct, and the 'Bridegroom came' in 1874. We believe that the Midnight Cry was of God, and was fulfilled by the Bridegroom's coming, not because Brothers Miller and B----claimed it, but because the Word of God supports it."
Additionally, Russell was influenced by other Adventists like George Storrs and George Stetson. George Storrs convinced Russell that one does not have an immortal soul. Upon Storrs death Russell commented in the Feb. 1880, page 7 number: "The news of Bro. Storrs death (Dec. 28th, 1879), reached us too late for insertion in last issue. As then stated our brother had just entered his 84th year and was quite ill. He was we believe 'a faithful servant,' and will soon 'enter into the joys of our Lord.' We mourn the loss of a friend and brother in Christ yet, 'not as those who have no hope.' The great Deliverer is at hand and assures us 'I have the keys, of death and Hades.' " The June 1884 ZWT contains an article by George Storrs entitled "The Will of God." Not only did Russell esteem this Second Adventist, but Stetson as well. In the Nov. 1879 ZWT, is Stetson's obituary. "...The brother's dying request, that the editor of this paper should preach his funeral sermon, was complied with. About twelve hundred persons attended the funeral services, thus giving the evidence of the high esteem in which our brother was held."
It is also documented that many of the readers of the early Zion's Watch Tower had Adventist backgrounds. See
http://www.amazingforums.com/forum/GSTORRS/16.html
Whereas Russell discounts the name Adventists in the Feb. 1884 ZWT under "Our name," and never claimed to be one, it is clear that he fellowshipped with them from 1868 until 1879, had close associates and friends who were Adventists, learned from them and quit the staff of a Second Adventist publication, the Herald of the Morning, after having a disagreement with Barbour in 1878, to begin his own journal in 1879, Zion's Watch Tower and Herald of Christ's Presence. ( As an aside, please note that he believed this presence to have already occurred in 1874.)
It is not until the April 1, 1910 ZWT, page 119 that the name "International Bible Students' Association" is adopted as the name for followers of the Watch Tower. Although Russell claims to have started his Bible class in 1868, we have noted that the majority of these students of the Bible and associates were Second Adventists. It is clear that a separate group does not really begin to evolve until 1878 when Russell makes a break from Barbour. It is this group that becomes known as Bible Students.