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An improved form of Three-Circle Goniometer

Published online by Cambridge University Press:  14 March 2018

G. F. Herbert Smith*
Affiliation:
British Museum

Extract

In a previous paper the author pointed out the advantages of a goniometer possessing three graduated circles, and described an instrument of this type which had resulted from the addition of a two-circle arrangement to an ordinary reflective goniometer with a single (horizontal) circle. As was remarked in that paper, the adapted instrument has unavoidably the disadvantage that measurements can be made through little more than a right angle in any particular zone, with the single exception of the zone of reference, without readjustment of the vertical and third circles. The zone may, indeed, be completed by measuring from the diametrically opposite pole in the zone of reference; but difficulties occasionally arise in practice, and it is convenient to be able to measure through at least two right angles round the free end of the crystal by rotation of the horizontal circle only.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1904

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References

Page 1 note 1 ‘A three-circle goniometer,’ Min. Mag., 1899, vol. xii, pp. 175-182 ; a translation appeared in Zeits. Kryst. Min., 1900, vol. xxxii, pp. 909-216.

Page 1 note 2 ‘Preliminary note on an improved form of three-circle goniometer,’ Min. Mag., 1901, vol. xiii, pp. 75-76.

Page 12 note 1 ‘Über die von Professor E. von Fedorow herausgegebenen stereographischea Netze,’ Leipzig, Wilhelm EngeImam, 1897. Vide Zeits. Kryst. Min., 1896, vol. xxvi, p. 837.

Page 12 note 2 Min. Mag., 1903, vol. xiii, facing p. 820; and Zeits. Kryst. Min., 1904, vol. xxxix, facing p. 154.

Page 12 note 3 Min. Mag., 1904, vol. xiv, p. 18.

Page 13 note 1 von Fedorow, Cf. E., ‘Universalgoniometer mit mehr als zwei Drehaxen und genaue graphisehe Rechnung,’ Zeits, Kryst. Min., 1900, vol. xxxii, p. 481 Google Scholar ; and Stöckl, K., ‘Das Fedorow'sche Universalgonlometer in der Construction yon Fuess und die Anwendung dieses Instrumentes zur mechanischen Auflösung sphärischer Dreiecke,’ Zeits. Kryst. Min., 1904, vol. xxxix, p. 42 Google Scholar.

Page 13 note 2 Cf. Min. Mag., 1902, vol. xiii, p. 146; and Zeits. Kryst. Min. 1903, vol. xxxvii, p. 231.