Slide showing a line chart containing a 'curve plotted for the Bar and Infrabar series'. Slide shows a line chart containing a 'curve plotted for the Bar and Infrabar series'. Title below image reads: 'Fig. 29. - Curve plotted for the Bar and Infrabar series. Plotting actual and interpolated doses against percentage destruction of facets'. Y axis: 'Percentage destruction', ranging from 0 to 100. X axis: 'Doses', ranging from 2 to 6. Three symbols appear in several places on the line, one for the B series, one for the Bi series and one for the combination series. Late 19th to early 20th century