28 May 1805, Philadelphia. Since his 18 May letter in response to JM’s of 13 May he has received a dispatch from the Danish court about an agreement among the Northern Powers designed to prevent the introduction of yellow fever or other contagious diseases into the countries bordering the Baltic. Informs JM that from now on no merchant ship or vessel coming from the North Sea and destined for any Baltic port will be admitted unless the captain can produce the customs office certificate legally proving that the ship, on entering the North Sea, either by the Strait of Sund or by the Great or Little Belt, had halted at Elsinore, Nyborg, or Fredericia and taken clearance there, and that the board of health established at each of those places had, after making the accustomed examination, permitted the ship to pursue its voyage. Captains bound for Baltic ports will no longer be allowed to avoid halting at those places and obtaining a clearance as they have in the past. They will be refused all access to any port and will be obliged to retrace their course in order to submit themselves to the examinations and tests required by the boards of health.