Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 271
the attached photographs, showingmagnified sections of cultivated andnatural pearls, the mother-o-pearl centrein the cultivated type being clearlyshown, whilst it will be noticed that thenatural pearl is made up in a largernumber of layers. C 246 THE [LLUMINATING ENGINEEB (dec. 1921 As was pointed… … fkk \* M Wf- ^^j 9/ Fig. I. Sect ion of Nut ural Pearl. Fig. 2.-—Section of Japanese Cultured Pearl. INDUSTRIAL ILLUMINATION. A lecture on the above subjeol was de-livered before the Belfast Association ofEngineers on November 17th by Mr. < I.Herbert, who emphasised the importantbearing of…
Lighting
Internet Archive · University of Toronto Libraries · Public Domain Mark 1.0. Free to use for anything.
