Slide showing diagrams labelled 'P' and 'F1' of unknown male and female aspects. Slide showing diagrams labelled 'P' and 'F1' of unknown male and female aspects. At the top of the image are two sets of male and two sets of female symbols, below are two diagrams relating to 'P', which consist of lines and arrows. There is a drawn arrow from the female 'P' diagram to the first female diagram in 'F1'. Item 'F1' has four diagrams relating to it, two male, two female. No further information available. Late 19th to early 20th century