The Civil engineer and architect's journal, scientific and railway gazette (1839)
London : [William Laxton] · leaf 436
Description .—a is a simple stem, sustaining the mirror, which can beplaced in a more or less vertical position by means of 0 a joint fitted with athumb-screw, to admit of being tightened or loosened at pleasure, c is ahollow shaft, or column, in which the stem a is made to slide freely, d is afelt…
Architecture · Civil engineering · Science
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