With this letter there was enclosed a fifth contribution to the Transactions. This article is entitled, "Meteorological Observations made by William Dunbar, Esq., at the Forest, four miles east of the Mississippi, in Latitude 31° 28´ North, and in Longitude 91° 30´ west of Greenwich, for the year 1800; with remarks on the state of the winds, weather, vegetation, etc., calculated to give some idea of the climate of the country." In this article he says, "the frequent and rapid changes in the state of the weather in this climate furnish an excellent opportunity of verifying the vulgar opinion of the moon's pretended influence at her conjunctions, oppositions and quadratures; but truth compels me to say (what probably may be said of many similar persuasions) that after a continued and scrupulous attention to this object, I have not discovered any such regularity of coincidences, which might justify the reverence with which those traditional maxims are at this day received." After discussing a method of manufacturing ice by artificial means, he concludes this communication with the following observations on the storms of the Gulf Coast region: "It is evident that the circular course of the vortex followed that of the sun's apparent diurnal motion.--It is possible that if similar observations are made upon all hurricanes, tornadoes and whirlwinds they will be found universally to consist of a vortex with a central spot in a state of profound calm." Dunbar's next letter that is preserved in the Jefferson Papers is one to John Vaughan bearing the date of March 21, 1802. In this the writer says that he envies Vaughan's "happiness at the discovery of a complete skeleton of a mammoth." He makes some observations on the species to which this mammoth belongs and refers to recent discoveries of a similar nature in the interior of Asia and Borneo. He gives the results of recent geological observations on the nature of the soil and the stratification of the same as shown by the banks of the Mississippi at Natchez; also a discussion of stones, rocks, ores, mineral waters, petrifaction, etc. He requests Vaughan to inform Dr. Bartram that since writing him last, he has made several new discoveries of a botanical and zoological nature which he here describes. This letter also shows that Dunbar was one of the first Mississippians to resort to inoculation for protection against small-pox. He asked Vaughan to send him some fresh vaccine virus and stated that six children in his own family had never "had that disease, besides a lengthy list of Black people, both young and old." Vaughan complied with this request by sending the virus and asked Jefferson to do likewise, stating that "the Vaccine inoculation gathers strength hourly, _no_ respectable practitioner (of Philadelphia) opposes it."