著者

小泉 賢吉郎

出版者

日本科学史学会

雑誌

科学史研究 (ISSN:21887535)

巻号頁・発行日

vol.22, no.146, pp.65-72, 1983 (Released:2021-09-29)

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This article investigates 18th century speculations on the relation between electricity and magnetism In order to illustrate more clearly speculation on the relation between the two, theories on electricity and magnetism themselves in the latter half of the 18th century are first examined. Although most people at that time held a fluid (or fluids) hypothesis, there were some, such as D. R tenhouse and R Kirwan, who had non-fluid hypotheses, particularly regarding magnetism As to speculations on the relation between electricity and magnetism, surprisingly most people denied that there was any, which seems a .clear indication that there was at that time no lively debate on the issue During the latter half of the 18th century people in general in their discussions of the relationship, referred to the following two facts: first, that the shock of electricity can destroy magnetism, reverse its polarity, and render a needle magnetic; and second, that the Aurora Borealis disturbs a magnetic needle. It is interesting to note that especially the first fact was used as supportive evidence both by those who denied the relation and by those who endorsed it. Those who held a fluid (or fluids) hypothesis found it impossible to perceive of a relationship between electricity and magnetism given the fact that while a magnet could be electrified, yet no changes were observed. In their terminology, an electric fluid (or fluids) and a magnetic fluid (or fluids) coexist in the same body without effect It is clear that that which prevented them from thinking further was not a theory alone, nor a fact alone, but was a theory combined with a fact. Thus, this branch of knowledge was, at that time, a closed world. Some entirely new approach was necessary before a breakthrough could be made.