midnight
But at last every patient was made comfortable . Tim and Polly thanked them again and again . `` Now for our long homeward tramp , Limpy-toes , '' sighed Grand-daddy wearily . It was long past midnight when tired old Grand-daddy pulled off his boots . `` A great vacation day it proved , '' he yawned . `` Bless me , it has been the busiest day I ever lived ! And yet , I 'm glad that I am a doctor-mouse . ''