Brevetto del 1954 di un "surveying instrument", ovvero un generico strumento topografico dotato di cannocchiale ed eclimetro. Ideato da Allister L. Baker per conto della Keuffel and Esser Co.
"This invention relates to a type of; surveying instrument frequently used in, building. work. It is a further improvement over the. structure. dis closed. in contending application Ser. No. 790,902 filed December 10, 19.47. This-type of instrument is; chiefly used as a level butis alsov provided with means for. reading horizontal. and vertical angles."
Brevetto del 1960 sempre di A.L. Baker
"This invention relates to an optical instrument. including means for measuring angles of elevation With respect to the horizontaldirection. More specifically, the invention relates to such an optical instrument provided with an automatic zeroing device so that. the elevation angles may be read with respect to the true horizontal direction even, though the base of the instrument is not perfectly level. The invention is particularly useful. in surveying instruments where it is used. forthe. measurement of the angle of elevation of the line. of sight of the surveying instrument telescope"
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