Slide showing two graphs: Fig. 6.14: 'An Ideal Distribution of the U-shaped Form' and Fig. 6.15: 'Cloudlines at Greenwich in July: 1715 Observations. (table 6.14.)'. Slide shows two graphs: Fig. 6.14: 'An Ideal Distribution of the U-shaped Form' and Fig. 6.15: 'Cloudlines at Greenwich in July: 1715 Observations. (table 6.14.)'. Fig 6.14 is a line graph, Fig. 6.15 is a bar chart. In Fig. 6.15, the Y axis is labelled 'number of observations per unit interval' and ranges from 0 to 700. The X axis is labelled 'cloudiness' and ranges from 10 to 0. Late 19th to early 20th century