Treatise on Mathematical Instruments: Their Construction, Adjustment, Testing and Use Concisely ExplainedVirtue Bros. & Company, 1866 - 185 pages |
From inside the book
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Page 14
... ( plate 1 , fig . 1 ) : With centre o , and radius o A , describe the circle A B C D ; and through the centre o draw the diameters a C , and B D , at right angles to each other , which will divide the circle into four quadrants , A B ...
... ( plate 1 , fig . 1 ) : With centre o , and radius o A , describe the circle A B C D ; and through the centre o draw the diameters a C , and B D , at right angles to each other , which will divide the circle into four quadrants , A B ...
Page 16
... ( plate 1 , fig 2 ) we have laid down the hours and latitudes to a radius equal to the whole length of the scale , the other lines being laid down to the radius used in the fore- going construction . The Line of Chords is used to set off ...
... ( plate 1 , fig 2 ) we have laid down the hours and latitudes to a radius equal to the whole length of the scale , the other lines being laid down to the radius used in the fore- going construction . The Line of Chords is used to set off ...
Page 23
... VIL Draw on your dial plate two parallel VILL * That is , the degrees on each parallel must have to a degree of latitude the ratio of radius : cosine of the latitude of the parallel . lines , a b , c d , as a CONSTRUCTION OF DIALS . 23.
... VIL Draw on your dial plate two parallel VILL * That is , the degrees on each parallel must have to a degree of latitude the ratio of radius : cosine of the latitude of the parallel . lines , a b , c d , as a CONSTRUCTION OF DIALS . 23.
Page 24
... plate or triangular frame similar to this triangle , and of the thickness of the interval of the parallel lines a c and b d , being now made and set upright between them , touching at a and b , its hypothenuse or axis a g will be ...
... plate or triangular frame similar to this triangle , and of the thickness of the interval of the parallel lines a c and b d , being now made and set upright between them , touching at a and b , its hypothenuse or axis a g will be ...
Page 25
... plate in the form of a parallelogram , the breadth of which forms the height of the style or gnomon , and must be equal to the radius to which the tangents have been set off on the dial plate . It is set up between the meridian lines ...
... plate in the form of a parallelogram , the breadth of which forms the height of the style or gnomon , and must be equal to the radius to which the tangents have been set off on the dial plate . It is set up between the meridian lines ...
Common terms and phrases
accuracy achromatic adjustment altitude axis azimuth beam compasses bisected breadth bubble called chromatic dispersion clamp coincide colatitude compasses construction correct cross wires described diaphragm distinct vision Ditto ditto divided drawing edge equal error extent will reach eye-piece feet figure fixed focal length given number goniometer graduated half horizontal inches index glass instru instrument intersection IVY LANE latitude lens lenses limb line of collimation line of numbers line of sines logarithmic means measured ment meridian microscope number of degrees object-glass observed paper parallax perpendicular placed plane position primary divisions prism protractor quarter girt radius rays reading reflected image reflector refracting refracting telescopes represent right angles right ascension round secants sector sextant side Slide Rule sliding speculum spherical aberration spirit level square staff station subdivisions tangents telescope theodolite transit transverse distance triangle tube turning vernier scale vertical circle zero
Popular passages
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Page 98 - ... 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...
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Page 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.
Page 143 - ... 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...
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