Three plain glass prisms in wooden box with sliding lid.

These prisms are likely to have been bought by William Herschel or possibly made by either William or his brother Alexander, while William was carrying out experiments on the nature and temperature of light.

Alternatively, they may have belonged to William's son John or any one of John's 12 children all of whom were taught and pursued scientific interests and all of whom lived for at least some portion of their lives in the Herschel family home in Slough.