50 YEARS AGO

International conferences can be very stimulating affairs for those who attend, and the discussions, in particular, open up entirely new lines of thought. Publication of the proceedings can extend the stimulus to a much wider circle of workers, but only if the publication follows close on the heels of the conference itself... The proceedings of the symposium on nutritive aspects of preserved food...have been published approximately eighteen months after the conference took place; despite this delay, many of the papers are still badly in need of editing, the English sometimes being so poor that a sentence must be read several times over before its meaning can be grasped.

From Nature 21 July 1956.

100 YEARS AGO

“The day of the week for any date” — We assign a number for each month in accordance with the old style, beginning with March, so that the last four months are numbered according to their Latin names, as follows: January, 0; February or March, 1; April, 2; May, 3; June, 4; July, 5; August, 6; September, 7; October, 8; November, 9; December, 10; next January 11; next February, 12. For a Leap Year, January and February must count as 11 and 12 respectively in the preceding year. It is only in dealing with the month-number that anything not straightforward and obvious is involved. The rule then runs as follows:

A. For the century: divide by 4 and calculate 5 times the remainder.

B. For the year: add to the number the quotient obtained from divisor 4.

C. For the month: multiply by 4, and negate the units digit (i.e. subtract instead of adding it).

D. For the day retain the number unchanged.

Then add together the results A, B, C, D (casting out sevens, of course, as you proceed), and the result gives the required day of the week...

Examples—1815, June 18 (Battle of Waterloo).

A. For century: 2+5=10≡3

B. For year: 15+3=18≡4

C. For month: 4×4 gives 10−6=4≡4

D. For day: 18≡4

A+B+C+D=15≡1, i.e. Sunday

From Nature 19 July 1906.