of the construction of the tables, and may be very long either before or after that period. Suppose, for example, that in constructing tables of the sun's motion, we are to set off from the beginning of the present century, and that we make the sun's place for the beginning of the year 1801 more advanced by half a degree than it was in reality. Suppose also that the mean motion set down in our tables is erroneous, in a way opposite to the former, and is less than the truth by 1" in a year. The place of the sun then, as assigned from tables for every year subsequent to 1800, will, from the first of the above causes, be half a degree too far advanced, and, from the second, it will be too little advanced, by as many seconds as there are years; when the number of years become as great as that of the seconds in 30', that is, when it is equal to 1800, the two errors will destroy one another, and the tables will give the place of the sun perfectly exact. Were we, therefore, to ascertain the age of the tables by Mr. Bentley's rule, we should commit an error of 1800 years; from which we may judge of the credit due to that rule, as a guide in chronological researches."
Here the reviewer's plausible sophistry may be clearly seen through. He assumes an error in the sun's place at the epoch of the tables of 30", and an error in the mean motion of 1" per year. All this,
