Description and application of the semaphore with glas panels, which is clearly visible on both bright and dark backing, no matter whether the source of light be before or behind the onlooker
Publisher: G. Maas
Published: 1860
Place of publication: Berlin
Language: eng
Notes: Signed: Berlin ... The inventor, G. Maas ...

At head of title: German patent no. 147953 ... American patent no. 739891 ...

Broadside.