45, COBNHILL, E.C., AND 122, REGENT STREET, W., LONDON. 



103 



143. New Self-Timing 

 Anemometer (Patent). This 

 improved instrument dispenses 

 with the use of a watch. By hold- 

 ing the Anemometer in the current 

 of air to be measured for a few 

 seconds it will correctly indicate 

 its velocity per second. 



Price, tig. 113. 500 



, INSTRUCTIONS FOR USE. 



This instrument is held up 

 with its back facing the current of 

 air to be measured. When the 



. 113. vanes have revolved for a few 



seconds, press the spring button at A, the large hand then indicates feet per 

 second. When read release the spring button. Should the velocity be such 

 that the hand travels more than one revolution, then read the inner circle of 

 figures. The small hand shows whether the outer or inner circle should 

 be read. 



NOTE. As every instrument is graduated at each unit by actual experiment^ no 

 allowance has to be made for friction. 



