The Post Office was at no time entirely dependent upon its regular sailing packets for the carriage of the mails. The merchant marine of England had been increasing with her growing commerce, and provision was made in the acts of 1657 and 1660 for the carriages of letters by private vessels. By the latter of these acts the conveyance of letters to foreign countries had been restricted to English ships under a penalty of £100 for every offence. It was decided in 1671, on the occasion of the wreck of one of the regular Irish packets, that it would be better to use a Dutch-built ship on account of its being much more seaworthy in the choppy swell of the Irish sea. Accordingly an order-in-council was issued, allowing a vessel built in Holland to be used, and providing for its naturalization.[517] By the act of 1660, letters arriving in private vessels were to be given to the postmaster at the port of arrival so that they might be forwarded to London to be despatched to their destination after being charged with the postage due. Masters of vessels were offered no inducement to deliver the letters to the postmaster nor was any liability incurred by neglecting to do so. The post farmers, however, agreed to pay a penny for every letter delivered by a captain on his arrival. This was the origin of ship letter money.[518] [517] _Cal. S. P. D._, 1671, p. 203. In 1793, owing to a scarcity of English vessels and as a war measure, permission was given to send English letters to Spain and Portugal by means of Spanish ships (33 Geo. III, c. 60). [518] Joyce, p. 73. No attempt had ever been made to collect postage on letters conveyed by private ships except for the distance which such letters might be carried by the regular posts within the kingdom.[519] In 1799 an act was passed under the following title: "An Act for the more sure conveyance of ship letters and for granting to His Majesty certain rates of postage thereon." The Postmasters-General were given authority by this act to forward letters and packages by other vessels than the sailing packets. On letters brought in by such vessels, 4_d._ was to be charged for a single letter and so in proportion. This was to be in addition to the inland postage and 2_d._ was to be paid to the master for every letter handed over by him to the Post Office. The net revenue so arising was to be paid into the Exchequer. No postage was charged on letters carried out of the kingdom by private vessels[520] until 1832, when permission was given to charge packet rates. It was forbidden to send letters by these ships except through the Post Office unless such letters concerned only the goods on board.[521] In 1835 that part of the act of 1711 forbidding letters to be sent out of the kingdom except in British ships was repealed.[522] [519] It is true that by the act of 1711, a penny was to be charged for every ship letter; but this was to go to the master of the ship. [520] 39 Geo. III, c. 76. [521] 2 Wm. IV, c. 15.