The letter is undated, but based on the reference to Darwin's "Loves of the Plants," it must have been written after the first publication of that poem in The Botanic Garden in 1791. Darwin describes Cosway's painting in a note to line 413.
The "work of the Gallery" that Cosway refers to may be her series La Galerie du Louvre (1802).
Part of the letter has been cut away, leading to significant loss of text.
With address.
Saying that she was happy to hear from Mrs. Dalton twice, but never received a long letter she had mentioned; requesting that Mrs. Dalton give her compliments to Mrs. Blair and "ask her if she has received my work of the Gallery as I have been told that they would not take it at her House in her absence"; recommending that Mrs. Blair choose "the Brown as the colord I am very much dissatisfied with the execution"; mentioning that the fourth number is coming out with alterations and improvements; saying that, several years ago, she painted a picture that was described in the poem "The Loves of the Plants" and that she has more recently painted something similiar; adding "I wanted to send it to Mr. [Richard] Cosway but he has no room to hang it up & it is too large and it would be a pity to have it about the ground"; writing "I cannot say much on my own picture but that I am very fond of the subject. It is 'Eros the love creator dividing Chaos'... from Hesiod & others"; asking if any of Mrs. Dalton's friends might be interested in it; mentioning a financial arrangement whereby "something would be given every month to a person in England to whom I know I will be of use"; including after her signature a small watercolor version of "Eros the love creator dividing Chaos."