Visible spectrum

From Alan C. Larman Your item on ultraviolet vision  (22 February, p 7) reminded me of the time I discovered I could see a little way into the ultraviolet. In my first year at university, we were measuring the wavelengths of the spectral lines in the potassium vapour spectrum.  I was taking much longer than  the rest of the group, so the tutor came over to see why. He looked  at my results and exclaimed,  “You can’t see those!” So I lined  up the spectroscope on three of the lines while he checked the textbook. “You’re right,” he admitted. “You’re seeing ultraviolet.”  In a long and very varied  career since then, I have had many opportunities to check, and I can definitely see a short distance into the ultraviolet. It would be interesting to know if any other New Scientist readers can do this.  I have met only two other people who have this ability. Congleton, Cheshire, UK