In the latter half of the twentieth century the development of Copernican studies has been highly remarkable. The author surveys from his personal point of view this development, which is divided into two periods. The first period is the time from the end of the Second World War to 1970, and the second period is the time from 1970 to the end of the last century. The year 1970 was really significant in the advance of Copernican studies, for in this very year two new learned journals relating to Copernicus began to be published at once: Journal for the History of Astronomy and Studia Copernicana. After he has pointed out some characteristic aspects of Copernican studies in these two periods respectively, the author proposes a few problems on Copernicus and his intellectual environment. Among others he emphasizes the importance of the concept of symmetria in Copernicus's new cosmology. If the role of this concept in the growth of his astronomical thought is properly recognized, the history of the Copernican Revolution will be viewed in quite a different perspective than before.
Friedrich Paschen (1865-1947) was one of the notable experimental physicists in Germany investigating the spectrum of hydrogen atom, especially spectral series, at the beginning of 20th century. As a part of research related to the spectroscopy, he was engaged with the heat radiation problems in the latter half of the 1890's. However his achievement of this area was not regarded as an important experimental work compared to his spectroscopic researches. This paper reconsiders Paschen's experimental research of radiation in late 1890's. In order to approach that topic, we mainly analyze the setup of radiation sources, the assembly of his bolometer and the range of wavelength of radiation and temperature of radiating bodies in his research. In this paper the features of his experiments are reevaluated in the context of development of radiation experiments during that time. It was certain that Paschen used the source of cavity radiation later than Lummer and Pringsheim and made confirmations of the radiation law in the narrower range of wavelength of radiation than other experimentalists in 1899-1900. However he did work out "numerous experimental confirmations " concerning the radiation law and did give any possible support for the establishment of Planck's radiation law until late 1900.
Based on the same presumption on the molding methods reported previously, the development steps of squeezing techniques in hand papermaking were surveyed and estimated from the analyses of hand papermaking conserved by minorities in and around southern China. The initial step of the shift from molding process was to make paper from squeezing in a deep vat dispersed plant fiber by using a screen fixed with frame. As the second improvement, a screen separable from frame was invented for production efficiency. The second step was to squeeze a suspension of plant fibers dispersed without mucilages by using the separable screen and frame and then to dry each a piece of wet sheet on a board or wall without pressing. The third step was to add the process of pressing a pile of wet sheets for improvement of paper bulk density and strength. In this pressing process, felts were first inserted between each wet sheet for preventing from mutually sticking these sheets. Finally the squeezing method was refined to reach the 'nagashizuki' technique by which a pile of wet webs are permitted to be pressed without inserted felts for peeling each sheet off.