Slide showing chart, untitled, with three curves, 'y' axis labelled 'Exhibition' and 'x' axis labelled 'Days'. Slide shows black and white chart, untitled, with three curves, 'y' axis labelled 'Exhibition' and 'x' axis labelled 'Days'. 'Y' axis scale begins at 0.10 and ends at 0.90. 'X' axis scale goes from 1-13. Two of the curves are mainly solid lines which start at 0.55 approximately on the 'y' axis. One curve is a broken line and begins at the very top of the 'y' axis. There is no further explanation and the slide is quite badly damaged. Late 19th to early 20th century