'During the whole stay on the Barrier I myself wore a pair of ordinary spectacles with yellow glasses of quite a light tint. These are prepared by a chemical process in such a way that they nullify the harmful colours in the sun's rays. How excellent these glasses are appears clearly enough from the fact that I never had the slightest touch of snow-blindness on the southern journey, although the spectacles were perfectly open and allowed the light to enter freely everywhere.' (R.E.G. Amundsen, The South Pole, London, 1912, p.87)