° ´ °´
Latitude left 52 36 N. Merc. prjctns. 3724 Longitude left 2145 W.
Diff. lat. 1 59 N. Diff. lon. 184 or34 E.
Latitude in 54 35 N. Merc. prjctns. 3925 Longitude in 18 41 W.
Sum of lats. 2)10711 Merc. diff. lat.201
Mid lat. 5335

To measure the Number of Cubic Feet of Water conveyed by a River in each Second.

In traversing regions watered by rivers and running streams, it not unfrequently becomes important to ascertain the speed at which they flow in their downward course towards the sea, and the following directions given by Captain George, R.N., are so perfectly clear and practical that both time and trouble will be saved by the traveller who follows them out in conducting his investigations. The data required are—the area of the river, section, and the average velocity of the whole current. All that a traveller is likely to obtain without special equipment is the area of the river, section, and the average velocity of the “surface” of the current which differs from that of its entire body, owing to fractional retardation at the bottom.

To make the necessary measurements, choose a piece where the river runs steadily in a straight and deep channel and where a boat can be had. Prepare half a dozen floats of dry bushes, with paper flags, and be assured they will act. Post an assistant on the river bank at a measured distance (of about 100 yards), down stream, in face of a well-marked object; row across stream, in a straight line, keeping two objects on a line in order to maintain your course. Sound at regular intervals from shore to shore, fixing your position on each occasion by a sextant angle between your starting place and your assistant’s station, and throw the floats overboard, signalling to your assistant when you do so, that he may note the interval that elapses before they severally arrive opposite him. Take an angle from the opposite shore to give the breadth of the river. To make the calculation approximately, protract the section of the river on a paper, ruled to scale in square feet, and count the number of squares in the area of the section. Multiply this by the number of feet between you and the assistant, and divide by the number of seconds that the floats occupied on an average in reaching him.

Important rivers should always be measured above and below their confluence, for it settles the question of their relative sizes, and throws great light on the rainfall over their respective basins. The sectional area at the time of the highest water, as shown by marks on the banks and the slope of the bed, ought also to be ascertained.

On obtaining Geographical Information from Natives or Frontier Colonists.

Many highly-accomplished travellers fail to obtain much reliable information beyond the actual limit of their own observation, because they do not sufficiently allow for the great difference in the manner of expressing a geographical idea between an educated European observer and an untutored savage; and yet it would not be too much to say that the latter has often enough a thoroughly practical idea of the district he actually knows.

The man who wants information must not talk latitude and longitude to a native or to an uneducated European, nor must he expect them to shape their answers to the form in which he expects to receive them; for if he does he may be told that “rivers run from the sea to the mountains,” and other absurdities, which are related as proofs of native stupidity, when they are in reality no more than discrepancies between the form of question and that of the answer. At the same time he must estimate the mental calibre of his informant, and avoid wearying him too much; for sometimes the native mind, over burdened with a succession of ideas, becomes confused, and not unfrequently suspicious, and in this last case actual falsehoods will be told, in order to gain time to find out the intention of the questioner, before the truth is revealed.