the reason japanese pagoda roofs decline in size is
Japanese pagoda The edge of a pagoda's eaves forms a straight line, with each following edge being shorter than the other. The more difference in length (a parameter called teigen (逓減, gradual diminution) in Japanese) between stories, the more solid and secure the pagoda seems to be. Both teigen and the finial are greater in older pagodas, giving them a sense of solidity.[5] Vice versa, recent pagodas tend to be steeper and have shorter finials, creating svelter silhouettes.