221 



reliable conclusion in this point of view coiild be drawn, 

 \ve will yet go to explain the method of the researches. 



The instruments eniployed were two anemometers of 

 the windmill type and a registering apparatus. 



The anemometers, which by and by have iindergone 

 some modifications, were definitly of following construction. 



Fig. 1 shows the anemometer well fixed on a wind- 

 vane 52.7 cm long, made of iron and zinkplate with two 

 wings in a distance of 12 cm from each-other on the end 

 /'. The axis of the windvane rested, in the bottom of a 

 brass-cylinder, on a steel-bullet. The brass-cylinder could 

 be fixed by a support on the roof. — On the axis of the 

 anemometer dd\ 4.5 cm of length, which went through two 

 layers in a vertical strong frame fffjg' and was supported 

 by a steel-pivot at d'^ was a screw, which caught a ver- 

 tical wheel O) with 60 teeth. 



The axis made an angle of 15° with the horizontal 

 plan and on its end were fixed the wings fig. 2. For the 

 investigation of the influence of the moment of inertness 

 two exemplars of the anemometer were constructed after 

 the same model, but with wings of different size. 



Fig. 2 shows that the wings, in form of trapezes, 

 were 4 in number. Their plan was inchned 15° to the 

 plan of the ring, which again was normal to the anemo- 

 meter-axis and hence formed an angle of 15° with the ver- 

 tical plan. Their dimensions were: 



The rings and the wings were made of aluminium. 



Every time the above named toothed wheel made a 

 turn, an electrical current was closed and by an electro- 

 magnet a point was marked on a drum, revolving with a 



