This document appears to be a listing of dates, captions, and a Twitter handle but does not contain any substantial information to summarize in 3 sentences or less. The dates and captions provided do not give enough context on their own to form a meaningful summary.

1. Tuesday, 25 June 13

2. PhotographcourtesyofCarolSomervellTuesday, 25 June 13

3. PhotographcourtesyofTheLondonSchoolofEconomics
Tuesday, 25 June 13

4. PhotographcourtesyofScienceMuseum/ScienceandSocietyPicture
Library
Tuesday, 25 June 13

5. Twitter: @timharford
Tuesday, 25 June 13