

Bi-metallic recording thermograph serial no. 45471 by Negretti and Zambra Ltd, London; with clock and recording drum mechanism by Gluck Barograph and Recorder Co Ltd, marked 7D 8RD
Bi-metallic recording thermograph serial no. 45471 by Negretti and Zambra Ltd, London; with clock and recording drum mechanism by Gluck Barograph and Recorder Co Ltd, marked 7D 8RD