One night,the gaoler decided to play a joke an his colleague

One night,the gaoler decided to play a joke an his colleague to find out if,after so many performance,he had managed to learn the contents of the letter by heart.after so many performance在这里是插入语吗?Then,quinting his eyes,he said;'The light is dim.Read the letter to me.'Finding that he could not remember a word of the letter either,the gaoler replied;'The light is indeed dim,sire.i must get my glasses.'quinting his eyes的quinting在这里是分词做定语吗?Finding在这里是分词作状语吗?如果是做状语做什么状语呢?