ing In Figs. 2 and 3 are represented all the various kinds of Trades Journal, a novel fac-simile printing process (Byford’s black diamond is now greatly used. The difficulty promi- patent) introduced by Messrs. 8. Straker & Sons, of Fen- STONE WORKERS TOOLS, church street, London, E. C., by which… … founds the blue-violet rays of the spectrum with blue-violet this space with as equal flames as possible, and in the experi- ments with the candles six were burned atatime. The re- sults of the measurements lay no claim to absolute exactness, because a whole series of inaccuracies, difficult, if…
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