VI. VELOCITY. 99 



410c. Lowne's Patent Magnetic Anemometer and 



Current Meter, for measurement of velocity of currents of air, 

 gas, and fluids. R. M. Lowne. 



In this instrument the registering works are enclosed in an air-tight cham- 

 ber, the connexion of the revolving fans with the works being made through 

 a sheet of brass by magnetism. This instrument is mounted on gymbals, 

 with direction vane for use on board ship. 



41Od. Lowne's Patent Ventilation Anemometer, origi- 

 nally introduced by Stanley. R. M. Lowne. 



This instrument measures the air by means of a fan wheel placed in a clear 

 opening, without any obstruction from the registering apparatus, which is in a 

 separate chamber on the same plane as the fans, so that the instrument is quite 

 flat for the pocket ; the whole of the works are of extreme sensitiveness, and 

 the axes of the fans run in jewels, the indicating hands give the current that 

 passes the fans in feet (after correction), and a lever above the dial throws the 

 registering works in or out of gear with the fans. 



410e. Mining Anemometer, for showing the velocity of cur- 

 rents in mines. Elliott Brothers. 



410f. Biram's Anemometer. Improved for Coal Mines. 



Francis Pastorelli. 



It consists of a broad brass ring; fixed to it is a metal frame which carries 

 three divided circles ; in the interior and centre of the ring is a spindle 

 which carries eight vanes ; on one end is an endless screw ; this works a series 

 of wheels, which give motion to the hands on the dials, which record the 

 distance travelled by the air current every foot up to 100, 1,000, and 10,000 

 feet. 



41Og. Dickinson's Anemometer. 



Joseph Casartelli, Manchester. 



This anemometer consists of a disc, or plate, made of light material, sus- 

 pended in a frame on delicate centres, having a balance weight attached to 

 the top of the fan. To one side of the frame is fixed on pivots a quadrant 

 opening out at right angles to the fan, and on it is marked the velocity of 

 the current in feet per minute, as indicated by the angular rise of the fan upon 

 which the current impinges. The advantage of the instrument consists in 

 the fact that it requires no timing as required by every other instrument, and 

 from actual experiment it is found as accurate as the most delicate instrument. 



410h. Improved Biram's Anemometer. 



Joseph Casartelli. 



The improvement in this instrument consists in the fan being made of light 

 material, thus greatly diminishing the friction, and rendering it a delicate and 

 useful instrument. 



41Oi. Biram's Patent Anemometer for ascertaining the 

 current of air in mines, air flues, &c. John Davis and Son. 



This anemometer registers up to 1,000 feet. At the bottom there is a tube 

 in which a stick may be inserted, so that the experimenter can stand at a 

 distance from the instrument, otherwise the current of air would be deflected 

 by the body of the experimenter. 



The vanes may at will be disconnected from the indices by means of a stud 

 at the side, thus rendering the process of timing more simple and exact. 



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