Transactions . railroad-work. Ina letter to me, Mr. Searledescribes it as provided witha detachable side-telescopeand a Saegmuller solar at-tachment. The side-tele-scope was provided with asmall longitudinal bubble,according to the practice in-stituted by the Brandis 1888 for the purpose ofinsuring a correct replace-ment of the auxiliary to cor-respond with the zero of thevertical circle. Mr. Searlesinstrument was furnishedwith an adjustable 120° ver-tical arc, similar to that inFig. 169, together with aprismatic eye-piece andstadia-wires. In my origi-nal paper* I quoted fromProf. Baker
Transactions . railroad-work. Ina letter to me, Mr. Searledescribes it as provided witha detachable side-telescopeand a Saegmuller solar at-tachment. The side-tele-scope was provided with asmall longitudinal bubble,according to the practice in-stituted by the Brandis 1888 for the purpose ofinsuring a correct replace-ment of the auxiliary to cor-respond with the zero of thevertical circle. Mr. Searlesinstrument was furnishedwith an adjustable 120° ver-tical arc, similar to that inFig. 169, together with aprismatic eye-piece andstadia-wires. In my origi-nal paper* I quoted fromProf. Baker the statementthat stadia-hairs were notintroduced in America until after the Civil War. This isincorrect, as the following passage from an American authorshows: The credit of having first introduced this method of measurement in thiscountry would seem to belong to Mr. John R. Mayer, a French-Swiss. It was usedby him as early as 1850, and subsequently during his connection with the U. S. * Trans., xxviii., Brandis Mine Transit.
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
