The names of the seasonal periods-or solar terms-indicate how the weather changes over the course of a year. The Directorate General of Posts has been releasing a series of stamp sets on the seasonal periods to give people today a greater appreciation of how the ancients lived. "The 24 Seasonal Periods-Autumn" set comprises six stamps, one for each of the six autumn periods: "The Commencement of Autumn," "Bounds of Heat," "White Dew," Autumn Equinox," "Cold Dew" and "Descent of Hoar Frost." Each stamp features a scene of life in an agricultural village during the designated period. The stamps are printed in se-tenant format. The designs of the six stamps follow:1. "Commencement of Autumn " : The torpid heat of summer is soon to pass, and with the imminent arrival of the cool clear days of fall the farmers are busy cutting crops and drying them in the sun, taking joy in the harvest.2. "Bounds of Heat": The heat of summer is gradually dissipating, but afternoons on sunny days are still very summer-like. Therefore, this period is called "Bounds of Heat." In this period, the farmers have finished dryingtheir harvested grains and have put them in granaries, which can be seen dotting the countryside.3. "White Dew": As the hot summer gives way to cool autumn, the temperature variation between day and night grows, and the cool nights cause the moisture in the air to condense as dew, whose sparkling beads cover the grass,flowers, and leaves, as if to highlight the arrival of the cool autumn weather.4. "Autumn Equinox" occurs when the sun is directly over the equator and the northern and southern hemispheres receive the same amount of sunlight. Nightand day are of equal length on the actual equinox, which is the first of this period. From this point on, there is a stronger sense of autumn in the air. It is also the time of year when the maple leaves turn red.5. During "Cold Dew" it is now deep into autumn.The temperature is dropping, and the leaves are falling from the trees. The green hillsides are turning yellow and brown. Upon the land there is a sense of the coming cold weather.6. By the "Descent of Hoar Frost" the sun is markedly favoring the Southern Hemisphere, and the Northern Hemisphere is turning cold. Sometimes in the early morning you can see a layer of frost upon the grass and trees: "The dew crystallizes into frost."