WE A THER FORECA S TS. 



317 



of the wind vane and is provided with four cams, each of which 

 extends over three eighths of the circumference and the central 

 points of which are a quarter of a circle apart. Four contact levers, 

 having rollers in their ends, hear on these cams; and, when raised 



Fig. 10. — The Anemometer. 



by the cams, the levers touch contact springs having a wire from 

 each that runs to one of four magnets beside the " triple register." 

 The levers and magnets are all connected with batteries. The mag- 

 nets act on armatures that are carried by levers, one for each magnet, 

 which have pens that make a dot on the paper of the cylinder every 

 time the magnet acts. One or two contact levers are always elevated 

 by the cams to make a contact. The cams are so arranged that only 

 one cam acts when the vane is directed to a cardinal point of the com- 

 pass; but, when it is between two such points, two of the cams are 

 acting. Thus the eight principal directions of the wind are indicated 

 by the four pens. The clock breaks the circuit of the vane except for 

 an instant each minute, so that the pen in action makes a dot eacli 

 minute. 



The velocity of the wind is registered by an instrument consist- 

 ing of a vertical shaft which carries four horizontal arms havin§| 

 sheet-metal cups on their ends. The wind acts more strongly on the 

 open faces than on the backs of these cups, and causes them to revolve 

 the shaft. Through gearing connected with the shaft, pins on an in- 

 dex close an electric circuit for every mile the wind travels, and the 

 current through a magnet of the triple register causes a sidewise mo- 



