## Treatise on Mathematical Instruments: Their Construction, Adjustment, Testing and Use Concisely Explained |

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accuracy achromatic adjustment altitude astronomical axis azimuth beam compasses bisected breadth bubble called chromatic dispersion clamp coincide colatitude compasses construction convex lens correct cross wires described diaphragm direction Ditto ditto divided drawing edge equal error extent will reach eye-piece feet figure fixed focal length given number goniometer graduated half horizontal inches instru instrument intersection latitude lens lenses limb line of chords line of collimation line of sines logarithmic means measured ment meridian microscope number of degrees object object-glass observed paper parallax pass pencils of light perpendicular placed plane polygons position primary divisions prism protractor radius rays reading reflector refracting refracting telescopes represent right angles right ascension round secant sector sextant side sliding speculum spherical spherical aberration spirit level square staff station subdivisions tangents telescope theodolite transit transverse distance triangle tube turning vernier scale vertical circle zero

### Populære avsnitt

Side 67 - ... that the sine of the angle of refraction bears a constant ratio to the sine of the angle of incidence...

Side 186 - Gd. 96. ASTRONOMY, by the Rev. R, Main. Is. 107. METROPOLITAN BUILDINGS ACT, and THE METROPOLITAN ACT FOR REGULATING THE SUPPLY OF GAS, with Notes, by D. Gibbons and R. Hesketh. 2s.

Side 90 - ... of this field of view. We must therefore place some fixed point in the field, of view, and in the focus of the eye-piece, and the point to which the measurement will have reference will be that point of the object viewed, which...

Side 185 - THE ENTIRE SERIES IS FREELY ILLUSTRATED ON WOOD AND STONE WHERE REQUISITE. The Public are respectfully informed that the whole of the late MB.

Side 24 - From the center at a draw the line ag for the axis of the gnomon agi, and from g let fall the perpendicular gi upon the horizontal meridian line an, and there will be formed a triangle ag i.

Side 135 - ... of them, those which apply to the eye-end of the telescope will answer much better ; the former having their errors magnified by the power of the telescope, will, in proportion to this power, and those errors, be less distinct than the latter. " In taking distances, when the position does not vary from the vertical above thirty or forty degrees, the handles which are attached to the circle are generally most conveniently used ; but in those which incline more to the horizontal, that handle which...