An example of simile in scientific writing:
"In an escarpement of compact greenish sandstone I found a small wood of petrified trees…The sandstone consists of many horizontal layers, and is marked by the concentric lines of the bark (I have a specimen). Eleven are perfectly silicified, and resemble the dicotyledonous wood which I found at Chiloe and Concepcion: the others, thirty to thirty-four in number, I only know to be trees from the analogy of form and position; they consist of snow-white columns (Like Lot's wife) of coarsely crystalized carbonate of lime. The largest shaft is seven feet."
Charles Darwin, 1835, letter to Prof. John Stevens Henslow.
The purposes of simile is offer a comparison to aid communication. Darwin would have been confident that Henslow (and anyone else he shared the letter with) would, although never having seen Lot's wife, be very familiar with the story, and have a image of her as a pillar of salt. Today, this would be less certain. (Anyone not aware of the fate of Lot's wife will find a brief account in The sins of scientific specialisation).
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