Sense of Cold

通常意義上，冷、熱是相對的。溫度是衡量物體冷熱程度的物理量。我們感覺到的冷暖是相對我們周圍的氣溫而言的。據說，人們穿三件貼身衣褲感覺比穿一件外套暖和，人的耳朵和鼻尖對寒冷很敏感。真是這樣嗎？

One feels warmer in the three pieces of underclothing than in the one thicker garment. What keeps one warm is not just the underclothing but the amount of air it keeps around the human body. Air is not a good conductor of heat. Three pieces of underclothing will hold three layers of air， whereas one piece， however thick it is， can hold only one layer which cannot， of course， keep so much heat， as three layers.

The ears and the tip of the nose are sensitive to cold， but not the pupils of the eyes. The sensation of cold or warmth in a human body is due to the receptivity of the points of sensation for cold and heat respectively， of which there are about 280，000 located in various parts of the human body. The points of sensation for cold are more concentrated over the ears， the tip of the nose， the waist， and the extremities of the four limbs， thus making those parts most sensitive to cold. The pupils of the eyes have no such points of sensation and consequently are least sensitive to cold.