Inside Out Library · Explore
Scientific American, Vol. 37, No. 14 (1877) (1877)
leaf 3
other copy is legible to people having the use of their eyes. The device affords a means of two blind persons maintain- taken to aid the exploration of a mining district. Other turies, may be gathered from the fact that-at the present great adits, such as those of the Hartz mountains and the ing a… … exist or may be generated. BecBg en © 1877 SCIENTIFIC AMERICAN, INCInternet Archive · Public domain (published before 1931). Free to use for anything.
More pictures from Scientific American, Vol. 37, No. 14 (1877)
More like this
