From British Journal of Anesthesia, 1965, volume 37, page 792.

Sketch by Dr. Thomas Beddoes in a letter to Jame Watt, February 27, 1795.  From ‘The Enlightenment of Thomas Beddoes: Science, Medicine, and Reform’ by Trevor Levere, published Taylor and Francis, 2016.  Page 26.

Gasometer built by James Watt for Dr. Thomas Beddoes for use at the Pneumatic Institute in Bristol, England where the effects of newly discovered gases were being researched.  Illustration found on Wikipedia.