How and at what points should the river be crossed? The solution of these problems depended on several factors that could be ascertained only by careful and extensive reconnaisances. In the Autumn of 1894, when the Japanese invaded Manchuria, the water was low and there was a ford near Suikochin. Now that the ice was melting in the mountains the river was deep. There was no ford and the Russians had taken away all the native boats. Seventy boats had been brought from Japan in the hope that they might be of service, but it was impossible to bring them up the river under the guns and rifles of the enemy. Many soldiers volunteered to swim the rivers, to cross on rafts and on inflated bladders. But General Kuroki would listen to none of these wild schemes, deeming them too hazardous before an enemy whose strength and purpose were unknown. Before the rivers could be bridged it was necessary to make sure that the water was not rising, for there was always the danger that while the ice on the lower stream melted, the upper stream would remain frozen and that ice floes would descend and sweep away the bridges. Cavalry were accordingly employed to place hydrometers in various places and to note the rise or fall of the river. As the waters of the Yalu rose or fell so rose or fell the hopes of General Kuroki and his staff. To reconnoitre the valley for battle was very difficult. All the rivers were wider, deeper and swifter than was expected. The main stream was four hundred and fifty mètres wide, and the smaller not less than one hundred mètres in width. Koreans reported vaguely that near the enemy’s main position the Ai-ho was fordable in two or three places where the water rose no higher than a man’s chest. A shower of rain or the melting of ice on the upper stream would drown these fords. Moreover, the lives of men and the issues of war could not be committed to native rumours. Careful investigation must be made. But the Ai-ho flowed only one thousand mètres in front of the Russian position and two thousand mètres behind their outposts. Reconnaissance was therefore impracticable as long as the enemy remained in possession of the islands, of Tiger Hill and of the hills to the North. Cossacks also patrolled the country from Tiger Hill to Antung and Westward beyond the mouth of the Yalu as far as Takushan.