James Ussher (d. 1656) wrote The Annals of the World setting the date of Creation Week in 4004 BC. Years ago his dates were in the margins of Bibles. The date of his death, 1656, is the same as the age of the Earth at the time of the Flood (1656). Evolutionist Stephen Jay Gould gave a fair evaluation of Ussher’s work:
Ussher represented the best of scholarship in his time. He was part of a substantial research tradition, a large community of intellectuals working toward a common goal under an accepted methodology… 
Ussher’s date for the beginning is no longer in vogue. A number of scientists helped promote the idea of an old earth including Pierre Laplace and Comte de Buffon.  Benoit de Maillet (d. 1738) estimated the age of the earth at two billion years based on his study of sea level decline. 
According to historian R. F. Foster, Ussher’s dating led to the “… practice among Irish antiquarians of showing scant respect for time.”  Leonard Bruno, Senior Science Specialist at the Library of Congress, claims that Ussher’s Annals is based on an “unscientific method.”  Ussher made reference to Scripture as well as many non-biblical sources (Livy, Tacitus etc.).
Others have kind words for Ussher, such as Marcus Tanner who called him, “… the greatest apologist the reformed Church in Ireland possessed.”  The Standard Dictionary of Facts, published in 1908 and edited by Henry Ruoff, actually used Ussher’s date for the beginning of the world (p. 54). Dorsey Hager, president of the Utah Geological Society, said in 1957,
Many millions still live in mental bondage controlled by ignorant ranters who accept the Bible as the last word in science, and accept Archbishop Ussher’s claim that the earth was created 4004 B.C. 
If we deny the numbers in Scripture, when do we start denying the words between the numbers?
What of Ussher’s family line? One of his most famous descendents was Clarence Ussher, an American evangelical missionary doctor. He was an Episcopalian and went to Turkey to aid Armenians in Eastern Turkey when they were being exterminated. There are at least 100 Usshers in the United States.
It is not strange that the heathens who are totally ignorant of the Holy Bible, should despair of ever attaining the knowledge of the world’s beginnings. Even among Christians, that most renowned chronographer Dionysius Petavius when asked his opinion concerning the creation of the world and the number of years from creation down to us, made this disclaimer: “That the number of years from the beginning of the world to our time, cannot be known nor in any way found out without Divine Revelation.” (Petav. de Doctrina Temporum, l. 9. c. 2.) – James Ussher
The fear of the LORD is the beginning of knowledge, But fools despise wisdom and instruction (Prov. 1:7).
1) quoted in Refuting Compromise by Jonathan Sarfati (Master Books, Green Forest, AR, 2004), p. 129.
2) “St Hutton’s Hagiography” by John Reed, Journal of Creation 22(2), 2008, p. 122.
3) Great Feuds in Science by Hal Hellman (Barnes & Noble, New York, 2007 ed.), p. 108.
4) Modern Ireland by R. F. Foster (Penguin Press, London, 1988), p. 49.
5) The Tradition of Science by Leonard Bruno (Library of Congress, Wash., DC, 1987), p. 200.
6) Ireland’s Holy Wars by Marcus Tanner (Yale Univ. Press, New Haven, CT, 2001), p. 92.
7) quoted in The Genesis Flood by John Whitcomb and Henry Morris (Presbyterian and Reformed, Phil., PA, 1961), pp. 116, 117.
Read Jay Hall’s book:
What is Young Earth Science (YES)? How old is the world? Are radiometric dating methods reliable? Is Darwinism substantiated by scientific evidence and valid arguments? How does the Renaissance of Catastrophism relate to the age of the Earth? Has plate tectonics occurred more rapidly in the past? These and other queries are answered in this exciting new fully documented work. This widely illustrated book features support from history, philosophy, geology, biology and physics. Discover this creative and multidisciplinary approach which provides affirmation that this planet is thousands of years old and not billions . . . (continue reading)