"But there's another trouble," said Frank. "At sea the navigator knows the run of his ship by means of the log, as we learned when we crossed the Pacific Ocean in our journey to Japan and China. How are we to 'throw the log' when travelling on land?"
"That is an easy matter," was the reply. "We will have several pedometers, or instruments for counting the steps. They are about the size of an ordinary watch, and worn in the pocket in the same way. Every step taken by the wearer is registered, and by knowing the length of our steps we can get very near the distance travelled. The pedometer is only approximative, and not exact, and the same is the case with the log on a ship.
DR. SCHWEINFURTH ASCENDING THE NILE.
"A famous African explorer, Dr. Schweinfurth, once had the misfortune to lose his instruments and all the records of his journey by fire. For six months after that calamity he counted his footsteps, noting hundreds by means of his fingers, and making a stroke in his note-book on reaching five hundred. The second five hundred was recorded by making a reverse stroke on the previous one, so as to form a cross, and in this way at the end of a day's journey every thousand steps he had taken was shown by a cross. He thus made account of a million and a quarter paces in the six months that he continued the practice.
"Dr. Schweinfurth says that the steps of a man are a more accurate standard of measurement than those of an animal. The camel, when urged to its full speed, does not increase the number of his paces but their length; while those of a man, at whatever rate he walks, are about the same. He suggests that any one may satisfy himself on this point by measuring his own footsteps in moist ground. He will find them varying very little, no matter what the rate of speed. Dr. Schweinfurth says his steps varied, according to the nature of the road, from twenty-four to twenty-eight inches, and we may set this down as the average step of a man of medium height.
AN AFRICAN HORIZON.