Excerpts from Rick Gunder's "Mormon Parallels," #136
William Miller, founder of the Adventist movement calculates 1843 as the end of the world.
By at least February 12, 1843, they [followers of Miller] came to Joseph Smith's attention during a visit by several young men from New York. Joseph "preached them quite a sermon. Shewed them that the error is in the Bible or translation and that Miller is in want of information." (1842-43 journal)
Joseph Smith believed that Miller's day of advent was set for April 3, 1843. On the preceding day, therefore, April 2, Joseph recorded his well-known revelation that Christ would not come until December 23, 1890 . . . [see D&C 130:14-15]
Sure enough, there was no Second Coming the next day, and Joseph observed triumphantly: "Monday, April 3d 1843 Miller's Day of Judgement has arrived, but tis too pleasant for false prophets"
On April 6, Joseph reiterated the "eighty-five years old" prophecy and promised that, "There are those of the rising generation who shall not taste death till Christ comes. . . . I prophecy in the name of the Lord God, and let it be written, that the Son of Man will not come in the heavens till I am 85 years old, 48 years hence or about 1890." Joseph then indulged in calculations based on biblical prophecy, referring ambiguously to the beginning of the "hour of his judgement" and figuring that if a day with God is 1,000 years, then an hour with God is "41 years, 8 months . . ."
Finally, after listening to Millerite predictions continue for a year, Joseph declared in a speech at the unfinished Nauvoo temple (March 10, l844):
. . . I take the responsibility upon myself to prophesy in the name of the Lord, that Christ will not come this year as Miller has prophecyed, for we have seen the bow. And I also Prophecy in the name of the Lord that Christ will not Come in forty years & if God ever spake by my mouth he will not come in that length of time & Jesus Christ never did reveal to any man the precise time . . . & all that say so are fals teachers.
The following description by Alice Felt Tyler ... conveys general impressions held at the time:
' . . . Preparations for the end were made by countless hundreds of joyous or desperate souls. White cloth was purchased and made into ascension robes. Nearly all secular business was neglected . . . Voting was light . . . Tents were put up outside cities . . . and hundreds of people assembled on the night of October 21  to keep their vigil together. No provision was made for food . . . the tension was intolerable . . . There were several suicides, and as the dawn of October 23 served notice that "time continued" regardless of prophecy, some heart-broken Millennialists were led away insane. '