During the ten years subsequent to the opening of the retail establishment in Copenhagen, the output of the factory must have been very extensive. It is interesting to find that in 1790 the Custom House regulations relative to the subject are as follows: "Foreign china is prohibited, because the manufactory at Copenhagen, which is at the charge of the State, has been of late productive enough to supply the two kingdoms with an article of luxury, more than of necessity. Painted earthenware is likewise prohibited, from its resemblance to china being so great that many may be induced to purchase it instead of a more valuable article; but plain earthenware, being more generally necessary, is allowed, as is also the porcelain brought over by the East India ships belonging to the Asiatic Company." =A Contemporary Account of the Factory.=--The testimony of two foreign critics who visited the factory in 1790 is a valuable record, as they produced authoritative statistical volumes on Northern Europe. Their opinion assists the modern student in forming an estimate of the relative value of the Royal Copenhagen porcelain as compared with that of the great contemporary factories, especially Meissen. In _Les Voyages de deux François dans le Nord de l'Europe_ (the Chevalier Louis de Boisgelin and the Comte Alfonse de Fortia), published by the latter, the trade and manufactures of Denmark receive full treatment. We quote from the English edition, _Travels through Denmark and Sweden: to which is prefixed a Journal of a Voyage down the Elbe from Dresden to Hamburgh, including a compendious historical account of the Hanseatic League, by Louis de Boisgelin, Knight of Malta, with views from drawings taken on the spot by Dr. Charles Parry_. This was published in two quarto volumes in 1810. The author states that the former volume written by his fellow-traveller is so rare that it is hardly possible to procure a copy "either of the original edition or of the counterfeit one produced in Germany." The details in regard to the factory as it then existed are very interesting. There were three large and two small ovens; one of these was the first employed by Müller when he produced his hard porcelain. The ovens were of brick. A firing lasted eighteen hours. It took four days to cool. "These ovens are capable of firing eight complete services at once, whereas those of Saxony cannot take in more than three. The fire here is so well distributed that in many of the firings of fine porcelain the loss sustained is scarcely more than ten rix-dollars."