Original fair copy of his poem titled "40 Signs of Rain," that he has written in full holograph. Above the title he writes, "Original Poem by Dr. Jenner." Apparently each time he wrote out this poem it was slightly different. The poem is also known as "The Signs of Rain." Poem variations include the secondary title, "Forty Reasons for Not Accepting an Invitation of a Friend to Make an Excursion with Him." According to the "Friend's Intelligencer" Jenner wrote this poem as a form of declining an invitation to go for a "country excursion one month in June on account of doubtful weather." This poem and "Address to a Robin" are Jenner's best known poetic works. In the year prior to Jenner having penned this copy of "40 Signs of Rain," he had been appointed as Physician Extraordinary to King George IV in 1821, and in 1823, he presented his "Observations on the Migration of Birds" to the Royal Society. It was copied in various publications, although when the first year of publication was is not clear (or not known). Over the years it was printed in Leavitt’s Farmers Almanac, “June [A Collection of Poems],” edited by Oscar Fay Adams (1886), “Gentleman’s Magazine, Volume 96 (1826) and other books and magazines. Nevertheless, it seems to have been lost for some years, with authorship questioned. In the November 21, 1970 issue of the British Medical Journal, J.F. Mayne writes saying, “In the summer of 1957 there was a discussion in your correspondence columns about the authorship of that delightful little poem "Signs of Rain." …These notes were taken by me from the” Life of Edward Jenner” by his friend and neighbor, John Baron, M.D., F.R.S., late senior physician to the General Infirmary, Gloucester, published in 1838 with a second edition in 1850… "This work has been composed from materials of the most authentic description, the whole of the notes and correspondence of Dr. Jenner having been put into my hands by his executors. Great care has been bestowed in tracing this history… Dr. Baron writes "His recreations from his more severe studies consisted in the cultivation of polite literature; and occasionally he sought an acquaintance with the Muses. He had a peculiar facility in conversation of clothing his remarks in the gay and lively colors of poetry. The reader will be gratified by perusing his Address to a Robin, Signs of Rain, and Berkeley Fair. I have seen him in his latter years after many cares had often weighed heavy upon him shake them entirely off; he would then take up a humorous strain and sing one of his own ballads with all the mirth and gaiety of his youthful days." This settled the authorship, once and for all, of Jenner's poem. _.
Jenner was a keenly observant naturalist and also fond of expressing himself in songs, or poems. In the poem offered here, as well as his other poems, he presented his detailed observations of his surrounding environment in verse form almost as a means of conversation. In a letter to his friend, Edward Gardner, Jenner remarks on his poetry writing. "I wish I could give up, or, at least, suspend the little acquaintance I have made with the Muses. Every time I begin a bagatelle, I almost swear it shall be the last...."