If a wind vane has one electrical contact, we can receive two kinds of signals, namely opening and closing, through one circuit. Therefore, when the vane has four contacts, we can receive 2⁴=16 kinds of signals as the permutation of opening and closing of these four circuits.
The author has invented a new distant anemoscope, and its construction is as follows. Under the wind vane, there is a distributor with four sets of commutating segments A, B, C and D. Fig. 1 shows the distributor schematically, in which the blank parts are made of conductor and the hatched parts are insulated. Four brushes are fixed to the rotating axis of the vane and contact electrically to the segments. From the distributor and the brushes, five wires, constituting four circuits, are led to the indicating part and connected to four electro-magnets respectively.
In this indicating part, there are six circular plates (Fig. 3.) parallel to each other. Two of them are fixed to the frame, and on each plate 16 windows, corresponding to the 16 directions of the wind vane, are bored in equal distance on a circle. Between these two plates, the other four plates A, B, C and D are set. Each of them has also 16 windows but not in equal distance, and is rotated π/16 by the magnet clockwise and counter-clock-wise alternately, when the circuit is opened or closed. Behind these plates, there is a lamp, and in front of them, a milky glass plate, with etched figures N. NNE, … etc. corresponding to the windows.
When the wind vane situates in one direction, some of the circuits are closed and the magnets of these circuits act on the rotatable plates, and only one of the windows is opened. Therefore we can observe the wind direction instantaneously at a distance from the vane.