The purpose of this paper is to examine the development of optical design technology of Japanese photographic lenses by analyzing some historical documents of optical designs, patent specifications and the correspondence between Ryozo Furukawa (an engineer of Nippon Kogaku K.K.) and Tatsuhiko Arakawa (an employee of Nippon Kogaku K.K.). The first Japanese photographic lens "Hexar " was developed by Hiroo Mouri of Rokuoh-sha with the assistance of Kogoro Yamada (an engineering officer of the Imperial Japanese Navy) in 1931. It was manufactured making use of Seidel's formulae and ray-tracing. Kakuya Sunayama (a designing manager of Nippon Kogaku K.K.) directed photographic lens technology in Nippon Kogaku K.K. from 1928 to 1937. Photographic lens technology is dual-use technology. In both cases, the demand by the military that needed aerial cameras advanced photographic lens technology. Later this outcome was transferred to civilian use. The military demanded high quality photographic lenses which met the high cost. Up until about 1935, private companies had sophisticated optical design technology and mass production facilities for photographic lenses. They also owned the data of the photographic lens designs and the technological accumulation of optical designing. It has become clear that the Japanese "original optical designs of photographic lenses " were established around 1938.

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To exemplify that the level of Japanese physics during late-Meiji and Taisho era was higher than hitherto considered, the status in the history of early quantum theory of Jun Ishiwara's two papers published just before and after his studying in Europe is explored. The first one is his 1911-1912 paper, "Contributions to the Theory of Light-Quantum. " In Part II of this, he derived Planck's radiation formula, presuming not only individual light-quanta, but also their complex named "light-molecules. " His approach entailed already the essence of Bose statistics, with light molecules playing the role of Bose's phase-space cells presented in 1924. De Broglie utilized in 1922 the same term "light-molecule " and the same series expansion of Planck's radiation formula as Ishiwara used in 1911, which subsequently led de Broglie to introduce the concept of "phase-wave. " In Part IV of Ishiwara's 1911-12 paper, in order to explain the wave-like behavior of radiation, he associated to light-quanta minute electric and magnetic vectors, which played almost the same role as de Broglie's phase-waves. The second one is his 1915 paper, "The Universal Significance of the Quantum of Action, " where Ishiwara presented, for the first time, the generalized quantum condition explaining at once Planck's radiation formula and Bohr's theory of atomic constitution. In the same year, Wilson and Sommerfeld presented their own generalized quantum conditions, which Einstein criticized as not independent of the choice of coordinates. In contrast, Ishiwara's quantum condition, if unnecessary factor 1/f is omitted, reproduced essentially the same results as Einstein's quantum condition presented in 1917.

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Michael Faraday introduced the idea of contiguous particles in order to explain the induction phenomena of electricity in 1837, thus denying the action-at-a-distance theory. However, he could not completely eliminate the possibility of action at a distance among particles, because he did not sufficiently consider rarefied air which could transmit electricity. He therefore had to assume the action at an insensible distance to account for the electric transmission in rarefied air. When he published his theory of induction, Faraday stated to consider the criterion of contact of particles only for a sensible distance, not discussing the action at an insensible distance. This idea of insensible distance came from the discussion of insensible distance stemmed from a similar argument in British empiricism, especially from the Scottish common-sense school tradition, e.g. John Robison and Thomas Thomson. They divided the qualities of matters into primary and secondary by invoking human senses as suitable criteria. While primary qualities were measurable quantities in mechanics, the secondary qualities consisted of primary qualities. Under the strong influence of Newtonian mechanics, these primary qualities included attraction and repulsion like universal gravity. Therefore it was not problematic to assume action at an insensible distance when the matters seemed to contact each other. Therefore, assuming action at an insensible distance was acceptable in the case of bodies contacting each other. This understanding led Faraday to the idea of contiguous particle.

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In 1891, Silk Association of America warned Japanese vice-consul in New-York that the quality of Japanese raw silk was sub-standard. It advised both an improvement of silkworm breeds and a reduction in Japan's more than 300 silkworm breeds. In 1893, the engineers at the Institute of the Ministry of Agriculture and Trade (I.M.A.T.) began applying themselves to the task, though there was little scientific knowledge of breeding by crossing. By 1910, I.M.A.T. could not develop suitable silkworm breeds. However silkworm breeders had achieved some improvements through hybridization. When Kametaro Toyama who had known the breeder's breeding by crossing, began to interbreed in 1900, he did not know Mendelism. But Toyama had learned about the heredity and variation of hybridization, through the book, 'The Germ-Plasm' of A. Weismann. In 1901, he read the paper of H. de Vries and found out about Mendelism. From 1902 to 1905, he continued silkworm cross-experiments in Thailand (then Siam). In 1906, he confirmed that Mendel's law could be applied to silkworm in his doctoral dissertation. And he insisted on making f_1 hybrid for improvement of silkworm. In 1909, he published the book, 'Sansyuron' which he presented his method of breeding based on Mendelism. Only in 1910 did the engineers at the I.M.A.T., including S. Ishiwata, accept Mendelism and Toyama's methodology. After that, under the leadership of Toyama, I.M.A.T. began improving silkworm breeds and succeeded in producing an excellent f_1 hybrid by 1913. As a result, the Japanese raw silk was rapidly improved in quality.

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