A Treatise of Mathematical Instruments, including most of the instruments employed in Drawing; for assisting the vision; in Surveying and Levelling, in practical Astronomy and for measuring the Angles of Crystals1864 |
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Page 5
... division upon any one of the scales . Now tighten the screw , and the compasses are set . To reduce or enlarge the Lines of a Drawing.- The line across the slider being set to one of the divisions , 2 , 3 , 4 , & c . , on the scale of ...
... division upon any one of the scales . Now tighten the screw , and the compasses are set . To reduce or enlarge the Lines of a Drawing.- The line across the slider being set to one of the divisions , 2 , 3 , 4 , & c . , on the scale of ...
Page 6
... division marked 4 or 5 on the scale . To take the Square Root of a Number . — The line across the slider being set to the number upon the scale of plans , open the points A and B to take the number from any scale of equal parts ( see ...
... division marked 4 or 5 on the scale . To take the Square Root of a Number . — The line across the slider being set to the number upon the scale of plans , open the points A and B to take the number from any scale of equal parts ( see ...
Page 8
... divisions from the plotting scale and protractor ( p . 33 ) . This point may also be used to prick through a drawing upon an intended copy , or , the needle being reversed , the eye end forms a good tracing point . A STRAIGHT EDGE . As ...
... divisions from the plotting scale and protractor ( p . 33 ) . This point may also be used to prick through a drawing upon an intended copy , or , the needle being reversed , the eye end forms a good tracing point . A STRAIGHT EDGE . As ...
Page 11
... division . Our figure represents the two diagonal scales which are usually placed upon the plane scale of six inches in length . In one , the distances between the primary divisions are each half an inch , and in the other a quarter of ...
... division . Our figure represents the two diagonal scales which are usually placed upon the plane scale of six inches in length . In one , the distances between the primary divisions are each half an inch , and in the other a quarter of ...
Page 12
John Fry HEATHER. 10 primary division , and it will reach beyond the beginning of this division , or zero point , a distance equal to one of the sub- divisions . Now divide the extent thus set off into ten equal parts , marking the ...
John Fry HEATHER. 10 primary division , and it will reach beyond the beginning of this division , or zero point , a distance equal to one of the sub- divisions . Now divide the extent thus set off into ten equal parts , marking the ...
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Common terms and phrases
accuracy adjustment ÆSCHYLUS altitude AMEN CORNER arc of excess arrows astronomical attached azimuth beam compasses bisected brass bubble called chain chords clamp coincide columns compasses construction correct cross wires described diaphragm difference Ditto ditto divided division drawing edge equal extent will reach eye-piece feet figure fixed focal length goniometer graduated Gunter's chain half horizon glass inches index glass instru instrument intersection latitude lens lenses light limb line of collimation line of sines logarithmic marked means measured ment meridian method microscope moved object object-glass observed parallax parallel plate screws pencil perpendicular plane position prism protractor radius rays reading reflected image reflector refracting telescopes refraction represent right angles right ascension round scale sextant side sixth column spirit level square staff station strument survey tangent telescope theodolite transit transverse distance Troughton's tube turning vernier plate vernier scale vertical axis vertical circle zero