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Preliminary note on an improved form of three-circle Goniometer

Published online by Cambridge University Press:  14 March 2018

G. F. Herbert Smith
G. F. Herbert Smith*
Affiliation:
British Museum
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Extract

In a previous paper the author pointed out the advantages of a three circle form of goniometer in the determination of the morphological characters of crystals ; the crystal is adjusted once for all, and measurements may be made in any desired zone. A description was added of such an instrument, which had resulted from the addition of a two-circle apparatus to an ordinary Fuess goniometer with a single horizontal circle. This instrument has been in almost daily use since the end of June, 1899, and the author is, therefore, in a position to appreciate the ease and celerity with which crystals, however small, may be in this manner measured. As was remarked in the paper quoted above, the adapted instrument has the disadvantage that measurements can only be made through little more than a right angle from the pole in which the zone to be measured and the zone of reference intersect, and, therefore, only half a zone can be measured without readjustment of the circles B and C.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 13 , Issue 59 , May 1901 , pp. 75 - 76
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1901

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References

Page 75 note 1 This Magazine, 1899, XII, 175-182; a translation appeared in Zeits. Kryst. Min. 1900, XXXII, 209-216.

Page 75 note 2 Ibid. footnote on p. 179.

Page 75 note 3 The same notation is employed here as before : A is the horizontal circle whose axis is fixed in space, B the vertical circle whose azis lies in a horizontal plane, and C the third circle.

Page 76 note 1 If preferred, the telescope and collimator may have separate tubes, but both must lie in a vertical plane and be turned through a right angle.