210 



Portable Anemometers. 



These instruments are extensively used in 

 studying and controlling the ventilation of 

 dwellings, public buildings, factories, mines, 

 etc. 



The velocity of the air current is measured 

 by means of a very light fan wheel, whose 

 revolutions are recorded on a dial. 



This fan wheel is very delicate, the van^s 

 being made of aluminum, and the axis of hard 

 steel runs in jewel bearings. 



The counting mechanism is enclosed in a 

 dust-pro?f case, and can readily be thrown 

 into or out of action by a disconnecting lever. 



The instrument is provided with a thumb- 

 screw for attaching it to a rod for use in meas- 

 uring the velocity of air currents at any point 

 on the surface of the earth, mine shafts, in 

 pipes, conduits or narrow channels. In this 

 case the c n unting mechanism is thrown in or 

 out of gear by pulling on cords of different 

 colors. 



This Anemometer is carefully rated and sup- 

 plied WITH A CORRECTION NUMBER. 



Anemometer, Counting up to 10,000, OOP 

 ft.; diameter of fan, Sin.; complete, packed in 

 polished wooden box, $25.00. 



D 



The Brunton Patent Pocket Mine Transit. 



A pocket instrument which takes the place of a sighting compass, clinometer, pris- 

 matic compass, and an Abney level or Locke's ley el. Weight 8 ounces. Price, $25. OO 



