Help:Talk page
Iceland spar (pp. 119, 354-355, and elsewhere) is a transparent variety of calcite used for optical purposes, and perhaps best known for its ability to produce a strong double refraction of light. Thus objects viewed through Iceland spar appear doubled. Rasmus Bartholin was perhaps the first to describe this property. Now note all the doubles in the errata: p. 87, line 12 has a doubled "be"; page 92, line 15 has a doubled "what"; page 334, line 19 has a doubled "of"; p. 552, line 22 has a doubled "be"; and so on. It looks to me as if the doubled words may be part of the calcite motif. Godshawl 13:16, 17 December 2006 (PST)