The construction of a railroad from Maulmain, _viâ_ Cheung Mai, to some point in South-western Yunnan would probably not encounter any physical obstacles more serious than is usually met with in railroad building. After entering the plain or plateau of Cheung Mai the engineering difficulties would be of little consequence until the mountains of Cheung Hoong were reached; and even there the elevation is not very great and there are no deep gorges, such as are met with on the Bhamo and Manwyne route. It is probable there are no insurmountable barriers on this route, and, judging from the accounts of Cheung Mai and Yunnan traders, there are no serious difficulties to be encountered. Until there is a scientific survey any expression of opinion as to the best track is little more than conjecture. From Cheung Mai to Cheung Rai there are two routes. One explored by McLeod and others, although not adversely reported upon, is certainly a difficult route; I traveled over it in 1880 to Cheung San and found the highest point passed over to be thirty-five hundred feet above the Cheung Mai plain, and the ascent is abrupt. The second of the two routes mentioned above has never been described; until 1880 this route had never been traveled by a white man. In January of that year I traveled over it, and found it, as I thought, possessed of advantages over the other road. Proceeding from Cheung Mai in a northerly direction, following the course of the Maping River to a point fifty-five miles north of Cheung Mai, thence in a direction east by north-east, at a distance of twenty miles from the Maping River we entered a large and fertile plain lying to the east and south-east of Cheung Rai, and separated from that province only by a low range of hills; traveling through this plain to the Ma-Kok River, and following the course of that river, the journey to Cheung Rai is a very easy one. This plain, situated to the east and south-east of Cheung Rai, although uninhabited at the time I visited it, was in the beginning of Laos history the most populous of all their provinces; ruins of the ancient city which was the capital show that at one time there must have been considerable wealth in the province. The name of this ancient city and now deserted province is Muang Fäng. A colony from Cheung Mai has recently settled in the province. This plain is distant from the Maping River only about twenty miles, and the highest point of the divide is twenty-six hundred feet above Cheung Mai――ascent very gradual. The plain is six hundred feet higher than Cheung Mai. A railroad from Cheung Mai (supposing connection between Maulmain and Cheung Mai already established), following the route indicated above, would encounter no serious physical difficulties in reaching the present northern boundary of the Siamese Laos territory.