Machinery and processes of the industrial arts, and apparatus of the exact sciences (1869)
Barnard, Frederick A. P. (Frederick Augustus Porter), 1809-1889 · Washington, Govt. print. off. · leaf 560
e divisionof the beam, it is only a matter of mechan-ical detail to give to the parts any direc-tion which may be found most conven-ient. For purposes of demonstration, orin the prosecution of concerted observa-tion, simultaneous observation of the same object is not only convenient,but is also… … Double Microscope.
Machinery · Scientific apparatus and instruments
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
