Lowell House's usual afternoon calm was interrupted yesterday when a couch caught on fire in Room P-22. While the bewildered occupants stood by helplessly, two quick-thinking members of the Yard police, Messrs. Grady and McNamara, seized the smouldering piece of furniture and hurled the mattress out of the window. As soon as it reached the ground, the mattress started to blaze, and after several buckets of water had failed to quench the flames, the day was saved by the appearance of the janitor with a fire extinguisher. The damage was pronounced negligible.