'INCUBATOR FOR THE MICROSCOPE STAGE'
MAKER: CHARLES HEARSON
c. 1920'S-1930's(after 1916)
SIGNED ON THE STAGE WARMER FRAME: 'HEARSON &Co, LONDON'
SIGNED ON THE INSTRUCTIONS:
'CHARLES HEARSON & CO., Ltd.,
68, Willow Walk, BERMONDSEY,
LONDON, S.E.1.'
SIGNED ON THE BULB: With an 'E' inside a triangle and the numbers '220 32' on another area of the bulb.