A general review of the packet services existing at the middle of the nineteenth century affords a very good example of the relative importance of these different systems of communication and of the principles on which the payment of subsidies was based. The inland packet service of the United Kingdom included, among others, the lines between Holyhead and Kingstown, Liverpool and the Isle of Man, Aberdeen and Lerwick, Southampton and the Channel Isles. This formed a necessary part of the inland postal service, and no attempt was made to meet expenses by levying a sea-transit postage. In the case of the Isle of Man the postage collected covered the cost of the packets and of the land establishment of the Post Office in the island. The expenses of the Shetland packets by themselves exceeded the postage collected, and the Orkney postal expenses were also greater than the revenue. The second class consisted of the packets plying between England and the colonies or between the colonies themselves, and included the lines to India, Australia, the Cape, the West Indies, and British North America. This class was and is by far the most important. Three-fourths of the whole annual subsidies paid by the Government for the packet service were paid to three great companies, the Peninsular and Oriental, the Royal Mail, and the Cunard Company. The first of these connected England with India and the Orient, the second with the West Indian colonies, and the third with the North American Provinces. The great cost involved in subsidizing these companies was excused on the ground of absolute necessity for a regular and rapid mail service between the mother country and her colonies. Of the lines furnishing communications with foreign countries, several were connected with and subsidiary to the colonial service, as the continuation of the Cunard line to the United States. The service to China was the most remunerative part of the system undertaken by the Peninsular and Oriental boats, and the same may be said of the foreign service of the Royal Mail Company. From a commercial point of view the Continental packets were perhaps the most important of all.[556] [556] _Acc. & P._, 1852-53, xcv, 1660, pp. 37-43.