the touch of his sensitive tongue. Besides, haven't you noticed that he goes badly adrift in his use of the names of colours? Anyhow, let's test him." For this purpose Thomas bought a child's box of wooden picture-blocks, and covered the faces of the cubes with paper of different colours very carefully selected so that their tone values and tactual and olfactory qualities should be identical. Any differences of odour that might be due to differences of pigment he blotted out by drenching the blocks in eau-de-Cologne. He then presented the "box of bricks" to Plaxy and Sirius. Plaxy at once produced a chequer of pink and blue squares. Sirius was obviously uninterested in the blocks, but he was persuaded to copy Plaxy's chequer. He put the pieces together quite at random. It was soon obvious even to Sirius himself that Plaxy saw something which he missed. He at once set about the same kind of self-education which he had undertaken in order to read. With Plaxy's aid he must discover the thing that had escaped him in the bricks, and then strengthen his powers of seeing it. Plaxy displayed coloured objects to him one after another, naming their colours. She showed him a coloured print and a monochrome photograph. Giles produced a flash-light with red and green glasses. But all was in vain. Sirius was quite unable to discover what colour was.
He was at first greatly distressed, but Thomas comforted him by assuring him that all dogs were colour-blind, and probably all mammals but apes and men. And he reminded Sirius that dogs were at any rate far superior in hearing and smelling. Sirius had long known that human noses were very poor instruments. He had often been contemptuous because Plaxy could not smell out her mother's track in the garden, or tell with her nose whether a certain footprint was Gelert's or another dog's. Moreover at an early age he was surprised and disappointed at her obtuseness to all the mysterious and exciting smells of the countryside after rain. While she mildly enjoyed an indiscriminate freshness and fragrance, he would analyse the messages of the breeze with quivering nostrils, gasping out words between the sniffs. "Horse," he would say; then after another sniff, "And not a horse I have smelt before." Or, "Postman! Must be coming up the lane." Or perhaps, "Sea-smell to-day," though the sea was several miles away behind the Rhinogs. A slight veering of the wind might bring him whiffs of a distant waterfall, or more fragrant odours of the moor, or peat or heather or bracken. Sometimes, gripped by some strange enticing scent, he would rush off to trace it. Once he came trotting back after a few minutes of exploration and said, "Strange bird, but I couldn't see him properly." On another occasion he suddenly rushed out of the house, sniffed the breeze, raced off up the moor, cast about till he picked up a trail, and then streamed along it round the hill shoulder. After an hour or so he returned in great excitement, made Plaxy fetch out the animal book and turn the pages till she came to The Fox. "That's him!" he cried, "Gosh, what a smell!" Once in the middle of a romping game in the garden he came to a sudden halt, sniffing. His hair bristled, his tail curled under his belly. "Let's go inside," he said, "theres some dreadful thing up wind." Plaxy laughed, but he seemed so disturbed that she consented. Twenty minutes later Giles arrived from school, full of the news that he had seen a menagerie pass along the road to Ffestiniog.
Giles was so tickled by Sirius's reaction that he clamoured for Sirius to be taken to see the wild beasts with the rest of the family, arguing that the little coward had better learn that bad smells were not really dangerous. After much persuasion Sirius consented to go. The experience had a lasting effect on him. As he entered the enclosure the appalling contusion of odours, some enticing, some formidable, tore his nerves as though (as he said long afterwards) all the instruments of an