Sir, - A number of amendments are needed to Frank McNally's item "The world may end at 6pm" (October 22nd). James Ussher published his chronology of the Old Testament in 1650, followed in 1654 by his continuation to include the New Testament, and he died in 1656. Firstly, at the beginning of this work he stated that God created Heaven and Earth at the beginning of the night which preceded the 23rd day of October, 4004 BC; Ussher nowhere mentioned the specific time of 6pm.

Secondly, Ussher brought this chronological analysis down to the year 72 AD, so that nowhere in this work did he even discuss the end of the world, much less set a date for it. Thus McNally's assertion that Ussher "went on to calculate that the curtain would come down on the whole production today i.e. October 22nd 1996" is quite without basis in Ussher's work. This date is in fact a calculation of McNally's, based on the Jewish and Christian tradition that the world would last for six thousand years, and it is moreover numerically flawed. As Prof. Mark Bailey pointed out to him, 6,000 years from October 23rd, 4004 BC, brings one to around October 1997; the precise date depends on whether each "year" of the 6,000 is taken to be a Julian, Gregorian or solar year.

Finally, Ussher died in Britain in very troubled times, only two years after he published the second volume of his chronology, so McNally's assertion that "Ussher won great fame in his day for his system of chronology" seems most improbable. It was not until the early 1700s that his chronology came to be printed in the margins of the Authorised Version of the Bible, and hence achieved a measure of fame.

To me, the most remarkable aspect of the story is not that Ussher published the date of 4004 BC for creation - Bede, Scaliger and Petavius before him had published similar such dates - but rather that the posthumous incorporation of his calculation with the sacred text of the Bible was done without any known ecclesiastical authority. - Yours, etc.

Dept. of Computer Science. Trinity College, Dublin.