Context: Bewick then describes an experiment which succeeded in keeping swallows alive in Britain for several years, where they remained warm and dry through the winters. He concludes:

Question: Who describes an experiment with swallows?
Answer: Bewick

Question: Where did this experiment take place?
Answer: Britain

Question: How did the experiment succeed?
Answer: they remained warm and dry through the winters

Question: How long did the birds stay alive?
Answer: several years