Four Corners Isaiah 11:12 "...four corners of the earth..."
Four Corners Revelation 7:1 "...four corners of the earth..."
Four Corners Revelation 20:8 "...four corners of the earth..."

The earth is STILL 1 Chron. 16:30 KJV "
Fear before him, all the earth: the world also shall be stable, that it be not moved."

more verses here.

Those that do understand Ellen White is a prophet, what does she say about this?

"I hope Brother Wilcox will be a truly converted man. This is his great need at the present time. He wants meekness, he wants humility, he wants genuine piety, and without it he is as sounding brass and a tinkling cymbal. His soul and your soul need the indwelling of Jesus. Whether the world is round or flat will not save a soul, but whether men believe and obey means everything."--Letter 43, 1887.

"The great question is, What shall I do that I may inherit eternal life? This is the science of what constitutes the higher education, and when this question is properly adjusted, the capabilities of the whole man are called into full exercise. There will be no agitation of the question whether the world is round or flat, but the whole burden of the soul is: What shall I do to inherit eternal life? We need now to make every talent that God has given us to be employed to His name's glory."  -- 21MR 414.5

"My answer was, "I have a message to this people in regard to the life they must live in this world to prepare them for future life which measures with the life of God. We have nought to do with the question whether this world is round or flat. [The important thing] is to serve God with full purpose of a renewed heart, sanctified and made holy by the cleansing blood of Jesus Christ."

Every issue will be brought in in various places by some persons who are not worked by the Spirit of God. Last night the Lord gave me words to speak to the people. Satan has a multitude of questions to bring in through various minds and ingenuity as all-important. Take the Word, plainly stating the truth for 1904; and the messenger that was sent of God had a message the same as the people need now. He was John the Baptist. --21MR 421.4,5

"There will be no agitation of the question whether the world is round or flat, but the whole burden of the soul is: What shall I do to inherit eternal life? We need now to make every talent that God has given us to be employed to His name's glory."  {21MR 414.5}  

The Sabbath Made for a Round World
God rested on the seventh day, and set it apart for man to observe in honor of His creation of the heavens and the earth in six literal days. He blessed and sanctified and made holy the day of rest. When men are so careful to search and dig to see in regard to the precise period of time, we are to say, God made His Sabbath for a round world; and when the seventh day comes to us in that round world, controlled by the sun that rules the day, it is the time in all countries and lands to observe the Sabbath. In the countries where there is no sunset for months, and again no sunrise for months, the period of time will be calculated by records kept... The Lord accepts all the obedience of every creature He has made, according to the circumstances of time in the sun-rising and sun-setting world. . . . The Sabbath was made for a round world, and therefore obedience is required of the people that are in perfect consistency with the Lord's created world."--Letter 167, 1900.  {3SM 317.1,2}

MR No. 839 - Keeping the Sabbath on a Round World
"We took Brother and Sister Haskell with our team to the station at Dora Creek. On the way Brother Haskell read an article on the day line, written to meet the fallacies that are coming in to make everything uncertain in regard to when the seventh day comes

It would be very strange if the Lord God of heaven should set apart a day for people to observe, and bless and sanctify that day, and give it to man and enjoin upon man that it be kept holy unto the Lord as a memorial that He made the world in six days and rested upon the seventh day and blessed the Sabbath day, and yet that day become so uncertain the world cannot tell definitely when the seventh day comes to us.

Here is a day given, and the Lord declares it shall be observe throughout your generations "for a perpetual covenant" (Exodus 31:16), as a sign of obedience and loyalty to God, and yet it is so obscured no one can tell when it comes! 
Oh, what fallacies men will resort to in order to carry out false theories. The Lord pronounced His blessing upon all who keep holy the Sabbath day. His commandments are given to a thousand generations, and when that period is ended the redeemed host shall be in the city of God and observed the Sabbath there, and especially come up to worship God from Sabbath to Sabbath and from one new moon to another." (Isaiah 66:23.)-- Ms. 173, 1897, pp. 4, 5. (Diary, June, 1897.) White Estate Washington, D. C. March 25, 1981  {10MR 342.1-3}  

"The cultivation of certain faculties to the neglect of others makes Bro. Andrews a one-sided man. When on the subject of the round world, Bro. Andrews could scarcely think or talk without dwelling upon this subject. He carried this matter to extremes. He wearied the readers and listeners to his lengthy arguments upon that subject. Precious time was used up in talking and writing upon that subject, which needed to be canvassed, but did not require so great thoroughness. Bro. Andrews was wearying himself and others, and at the same time was leaving undone the weightier matters. And more recently, months of precious time have been used up in wearisome labor, chasing after the dishonest quibbles of a man who once kept the Bible Sabbath, but afterward rejected it. His opposition is so great upon the Sabbath question that he is insane upon the subject." -{PH159 188.1}