Transactions . Hoskolds Engineers Theodolite, Improved. fectually prevents any possible lateral springing or vibratingeffects. Another important addition is the micrometer, the divided cir-cle or head of which is seen at the eye-end of the upper telescope,Fio\ 150. This divided head is attached to a finely-cut screw 54 REMARKS ON MINK-SI KYKYINO INST1UM HNTS. working in a metal frame which carries the spiders line index,over the divided comb, placed in the micrometer-box and in theFocus r tli» telescope. There is nothing new in this appen-dage; still, it is exceedingly useful and important in
Transactions . Hoskolds Engineers Theodolite, Improved. fectually prevents any possible lateral springing or vibratingeffects. Another important addition is the micrometer, the divided cir-cle or head of which is seen at the eye-end of the upper telescope,Fio\ 150. This divided head is attached to a finely-cut screw 54 REMARKS ON MINK-SI KYKYINO INST1UM HNTS. working in a metal frame which carries the spiders line index,over the divided comb, placed in the micrometer-box and in theFocus r tli» telescope. There is nothing new in this appen-dage; still, it is exceedingly useful and important in measuringsmall angles down to single seconds, and by estimation to the Fig. Hoskolds Engineers Theodolite, Improved. half of that quantity, and consequently any distance within therange of the telescope may be measured with the greatestfacility and accuracy. The simple trigonometrical formula re-quired to effect the calculation of the distance has already beengiven.* Fig. 148 shows the manner of mounting the circular * Trans., xxix., 980, February, 1899. REMARKS OH M I tTM I i;\ i:v l KG [H8TRUMBVTS. magnetic compass on top of the telescope. WTien no1quired it may be replaced by the long-trough magnetic com-pass, the needle of which baa an arc of only a few degreesBeen in Fig, L50; or b Long Bpirit-bubble may be inserted inplace of tlu- trough-compass, if required. The circular compass, Fig. 148, contains a magnetic needlewith a vernier mounted at each end reading to 16 of a magnetic bearing is no1 required bo fine, a plain needleis provided to take the place of the one with verniers. The plainBights of this compass are made very short and in pairs,
Size: 1357px × 1841px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
