Unknown device (? dust counter) ex Kew Observatory. Unknown Device (? Dust Counter) Ex Kew Observatory
Aitken's portable dust counter, no.116, M O 1A, in case with instructions, and wooden tripod, by Kelvin, Bottomley & Baird Limited, Glasgow, Scotland Aitken's portable dust counter
Tripod, for Aitken's portable dust counter, no.116, M O 1A, by Kelvin and White, Glasgow Tripod, for Aitken's portable dust counter
