The leading idea of the little book, as may be seen from the title, is that which agitates the public mind at the present time, and shows how important it is that England should keep the seas and protect the food and clothing coming to this country.[300] In connection with the commerce and trade of the country the official weighing of goods was a matter of great importance. As far back as the Saxon period standard weights and measures were preserved in the City of London, and with these the weights and measures throughout the kingdom had to conform. The King's great Beam or Tron was used for weighing coarse goods by the hundredweight, and the small beam or balance for silks, spiceries and goods sold by the pound weight. The King's weigh-house in Fish Street Hill, London, and the Tron Church in Edinburgh remind us of the old weighing machines of the country. It was formerly the custom to allow a margin to buyers at the Tron. According to the _Liber de Antiquis_, in 1305 the weigher allowed the buyer a draft of four pounds in every hundredweight. At the present day there is a survival of this custom in the tea trade and some others, for the importer gives a precisely similar 'draft' to the dealer, viz., one pound in every chest of tea of twenty-eight pounds.[301] Foreigners and strangers were not permitted, as a rule, to take up their residence within the walls of London for a longer period than forty days, and were subject to several restrictions as to trade. Exceptions were, however, made from time to time with various foreign towns. Natives of Denmark enjoyed the privilege of sojourning in London all the year through: in addition to which they had a right to all the benefits of 'the law of the City of London,' that is, they were entitled to the right of resorting to fair or to market in any place throughout England. Norwegians had the same right of sojourning in London all the year, but did not enjoy 'the law of the city,' as they were prohibited from leaving it for the purposes of traffic.[302] In February 1303 the King, by the _Carta Mercatoria_, granted exceptional privileges to foreign merchants, and these concessions caused great indignation among his subjects at home. A tax was exacted from these foreigners, and in 1309 the Friscobaldi were appointed by the King to receive the 'new custom,' and two years later he ordered their arrest for failing to render an account of the money received under that head. Their detention, however, was of short duration.[303] The Act was repealed in 1311, and again enacted in 1322, but with the accession of Edward III. it was again repealed. Foreign commerce is said to have been better governed than inland trade, for the King had an arbitrary authority in the regulation of trading. In dealing with the trade of London it is necessary to say something about the origin of Gilds; but this is a most difficult question, respecting which very different opinions are held by writers on the subject.