Just as Sir John Mandeville's expedition to the unknown regions of Asia in the fourteenth century has appealed to the hardy and brave sons of Britain from that early day; and in later times the famous ride of Colonel Burnaby to Khiva in our own generation has led Central Asia to be viewed as a land of mystery; so the plains of Rupert's Land, with the reputed Chinese wall thrown around them by the Hudson's Bay Company's monopoly, have been a favourite resort for the traveller, the mighty hunter, and the scientist. It is true no succeeding records of adventure can have the interest for us that gathers around those of the intrepid Verendrye, the mysterious Hearne, or the heroic Alexander Mackenzie, whose journeys we have already described, yet many daring adventurers who have gone on scientific or exploratory expeditions, or who have travelled the wide expanse for sport or for mere curiosity, may claim our attention. LEFROY'S MAGNETIC SURVEY. The discovery of the magnetic pole by Sir John Ross, and the continued interest in the problems connected with the Arctic Sea, the romance of the North land, and the dream of a North-West Passage, led to the desire to have a scientific survey of the wide expanse of Rupert's Land. The matter was brought to the notice of the Royal Society by Major, afterwards General Sir Edward Sabine, a noted student of magnetism. Sir John Herschell, the leading light on the subject of physics, succeeded in inducing the Society to pronounce a favourable opinion on the project, and the strong influence of the Royal Society, under the presidency of the Marquis of Northampton, induced the Lords of the Treasury to meet the estimated expenses, nine hundred and ten pounds, with the understanding that, as stated by the President, gratuitous canoe conveyance would be provided by the Hudson's Bay Company in the territories belonging to them. Lieutenant, afterwards General Sir Henry Lefroy, a young artillery officer, was selected to go upon the journey. A circular letter was sent to the Hudson's Bay Company posts by Governor Simpson, directing that every assistance should be given to the survey. Lefroy, having wintered in Montreal, was given a passage on May 1st, 1842, on the canoes for the North-West. Passing up the Ottawa and along the fur traders' route, he soon reached Sault Ste. Marie and Fort William; magnetic observations, accurate observations of latitude and longitude being made at the Hudson's Bay Company posts along the route. Kakabeka Falls and the various points along the Kaministiquia route were examined, and exchanging the "canot de maître" for the "canot de Nord," by way of Lake of the Woods and Lake Winnipeg, the observer arrived at Fort Garry on June 29th, having found Sir George Simpson at Lower Fort Garry.