John Bartram writes to Linnaeus and expresses his gratitude at having been nominated a member of the the Royal Swedish Academy of Sciences [Kungliga Svenska Vetenskapsakademien] in Stockholm. He adds a number of private conjectures (!) on phenomena that he has discussed with other scholars, and some observations in botany and mineralogy. He does not pretend to have the final solutions, but he is eager to describe them as queries to the Academy.
The first issue concerns Edmund Halley’s calculations of the evaporation from the oceans into the atmosphere, especially in comparison to the amount of water brought into the oceans by the rivers. In particular, the Red Sea must receive a considerable influx from the south, since the river ending in it brings very little. No overall conclusion is given, though.
The second issue concerns the role of the moon in causing the tidal variations of the level of the sea. He believes that the moon can not be the only or the main cause, and that the effect of Earth on the moon must be greater than the other way round.
The second half of the letter starts with a very long list of trees and shrubs, which Bartram had seen when travelling in the eastern parts of North America from Lake Ontario down to Florida. Observations of climate and its influence on the flora lead Bartram to a discussion on the role of ridges of mountains as moderators of climate, namely that they may prevent cold winds, snow etc. from spreading too far. That leads to the usefulness of mountains in general and as sources of mineral, mainly limestone and similar, in particular. The differences between kinds of limestone found at different places are noted, as the use made of it by the inhabitants.
[The letter was delivered to Linnaeus by the Swedish clergyman John Wicksell who left North America on 30 October 1773].