endeavored and tried, but time was wanting for the construction of the apparatus, the selection of stations, the instruc- Optical transmissions, however, have, over electrical to communicate with each other from great distances, ones, an advantage that in certain cases must make tion of operators,… … vessels communicate with and a longer one to a dash. each other and with ports by The apparatus now used are of Col. Mangin’s inven- means of flags by day and of other material connection between the two stations. lanterns by night, which, according to their relative tion. There are two kinds of…
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