The single gas jet burning at the end of the corridor was so dim and made so flickering a light that it added more to the shadows of the passage than it provided illumination. It was hard to discover which were realities and which shadows in the long gallery. Not a ray of light appeared at any of the transoms over the dormitory doors; yet that might not mean that there were no lights burning within the duo and quartette rooms in the East Dormitory of Briarwood Hall. There were ways of shrouding the telltale transoms and-without doubt-the members of the advanced junior classes had learned such little tricks of the trade of being a schoolgirl.