Acknowledgements

Every effort has been made to contact copyright holders. If any have been inadvertently overlooked the publishers will be pleased to make the necessary arrangements at the first opportunity.

Important: *** against any of the acknowledgements below means that the wording has been dictated by the rights holder/publisher, and cannot be changed.

Grateful acknowledgement is made to the following sources:

Figure 1: Thomas Jefferson (1743-1826) (colour litho), Peale, Rembrandt (1778-1860) / Private Collection / Peter Newark American Pictures / Bridgeman Images

Figure 2: Image by Hermann Traub from Pixabay

Figure 3: Image by OpenClipart-Vectors / 27429 images from Pixabay

Figure 4: US Patent Office, patent D187001. US Patent Image

Figure 6: Image by qimono from Pixabay

Figure 7: Robert Wilson

Figure 8: Image by Gerd Altmann from Pixabay