Wrote Letter L-069 to Joseph Williamson, as Grew had requested

February 14, 1678
Standard reference information
Collected Letters volume: 

This letter is known only by reference in another letter.

Letter L-070 of 18 March 1678 to Nehemiah Grew:

I kindly request you to acknowledge the receipt of this letter and to let me know whether my missive of February 14th found you. I addressed this letter to Sir Joseph Williamson in compliance with your request. I conclude this with greetings to the learned Philosophers and especially to Sir Joseph Williamson, congratulating him on his presidentship.

This letter is the only known letter from L. to Williamson, and there is no known reply. Williamson was the second president of the Royal Society, 1677 to 1680, preceded by William Brouncker, 1662 to 1677, and succeeded by Christopher Wren, 1680 to 1682. L. had addressed three letters to Brouncker in the fall of 1677 after the death of his regular correspondent Henry Oldenburg. Grew’s request that L. address further correspondence to the new president Williamson must have come in the lost Letter L-065 of 11 January 1678 that he and Robert Hooke sent to L.

Previous to this lost letter, L. sent Letter 37 [23] L-067 of 14 January 1678 to Hooke. After this lost letter, he sent Letter L-070 of 18 March 1678 to Grew. Both letters are in Collected Letters, vol. 2. He would continuing sending letters to Royal Society secretaries Grew and then Hooke instead of the president.

It is likely that this lost letter is a courtesy letter congratulating Williamson on his election as president.