Photo 1: Dust cloth filter with automatic knocking device (drawing no. 1735) (5x7 cm; unknown) Photo 2: Device for determining the dust content of air (5,5x7,5 cm; unknown) Photo 3: Schedule Tyndallometer (4x6 cm; unknown) Date: 1946 Keywords: devices, dustcloth filters, tyndallometers

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Size: 2221px × 3151px
Photo credit: © BNA Photographic / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: