## Mathematicians Of The Day

### 23rd October

On this day in 1852, Augustus De Morgan conveyed the

The postage stamp of one of today's mathematicians at THIS LINK was issued in 1977.

*Four Colour Problem*to William Hamilton, writingA student of mine asked me today to give him a reason for a fact which I did not know was a fact -- and do not yet. He says that if a figure be anyhow divided and the compartments differently coloured so that the figures with any portion of common boundary line are differently coloured -- four colours may be wanted, but not more ... Query cannot a necessity for five or more be invented.See THIS LINK.

The postage stamp of one of today's mathematicians at THIS LINK was issued in 1977.

Click on Ⓟ for a poster.

##### Born:

- 1865: Piers Bohl Ⓟ
- 1950: Richard Schoen Ⓟ

##### Died:

- 1780: María Andresa Casamayor Ⓟ
- 1944: Charles Glover Barkla Ⓟ
- 1985: John Semple Ⓟ
- 2007: David Kendall Ⓟ
- 2017: Charles Sims Ⓟ

#### Quotation of the day

##### From Charles Glover Barkla

The process of radiation may be, and is, continuous - at any rate within limits extending to far smaller quantities than the quantum.