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A modification of the stereographic projection

Published online by Cambridge University Press:  14 March 2018

John W. Evans
John W. Evans*
Affiliation:
Imperial Institute and Birkbeck College
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Extract

The change suggested relates mainly to the representation of the faces below the plane of projection. I propose that every face below that plane shall be represented by the same point as a parallel face above it.

If the two parallel faces are equivalent they will both be indicated by the same circular dot (accompanied, if desired, by the indices of either face). If they are not equivalent and only one be present, it will be represented by a plus sign (+) if it be above the plane of projection, and by a minus sign with a dot in the centre (-) if below it. If both are present but not equivalent, the double sign (±) will be used.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 15 , Issue 72 , September 1910 , pp. 401 - 402
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1910

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References

Note

1 The suggestion of the dot in the centre of the minus sign to represent the exact position of the point is due to Mr. H. Hilton. This will be indicated by the point of crossing of the + where that symbol is used either alone or in conjunction with the minus sign.