Transactions . 34. But for observation an instrument must be had wherewith < if thou likest it) thouart here fitted, both for observation and operation. It will be observed that, in contradistinction to the circum-ferentor, Stirrup refers to the theodolite; the allusion couldnot, however, have been made to the instrument of Sisson(1731); it refers, probably, to one of the style of Diggess, orsome improved form of it. Sturmy also described a sinical quadrant in 1669. That de- 786 REMARKS DPON SI RVEYINU INSTRUMENTS. scribed by Btirrup is very similar to thai constructed by AliBenash-Shihab,
Transactions . 34. But for observation an instrument must be had wherewith < if thou likest it) thouart here fitted, both for observation and operation. It will be observed that, in contradistinction to the circum-ferentor, Stirrup refers to the theodolite; the allusion couldnot, however, have been made to the instrument of Sisson(1731); it refers, probably, to one of the style of Diggess, orsome improved form of it. Sturmy also described a sinical quadrant in 1669. That de- 786 REMARKS DPON SI RVEYINU INSTRUMENTS. scribed by Btirrup is very similar to thai constructed by AliBenash-Shihab, in L834. This extraordinary instrument is pep-resented by Figs. 7 and 8. It was made of brass, inlaid withgold, silver and copper, and was, a few years prior to 1860, inthe possession of Mr. Morley, and in perfect condition. Oneof the sides of this instrument (Fig. 7) had various circles en-graved upon it, very complicated, and, as would appear, in-tended to be used for astronomical purposes. The opposite Quadrant of Ali Benash-Shihab, 1334. side, or second face (Fig. 8), also had the form of a quadrant,the outside circles of which were divided into spaces of 5°, in-creasing to 90°, each way, by a double set of figures. Thereare two inner circles, one of which is divided to single degrees,and the other to 30. Each side of the quadrant is also dividedinto spaces and figured from 5 to 60 degrees, and by an innerscale to 30 minutes. Corresponding to the angles and side-scales, the face of the quadrant is divided by 120 parallel lines, KIM UtKS I PON -i i:\ \ \ I N(l INSTRlM] —. i —i 61 with another series at right-angles; so that the instrument maybe railed n quadrant of the canon, representing the 1« Qgthof the natural sines and cosines, corresponding to the anglesrepresented on the quadrant. In the instrument under noti<each fifth sine Is inlaid with copper.* The original description of this instrument is largely miwill i Arabic names and characters. Similar
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
