98 SEC. 3, MEASUREMENT. 



It consists mainly of a water-tight globular shell of gun metal, pointed in 

 one direction, and terminating in the other in a long double vane, and is 

 carried by two pivots on a stirrup. Within the shell is a brass box, 

 suspended by girnballs in the manner of a ship's chronometer, and containing 

 a magnet with a graduated ring, and a train of clockwork. When the instru- 

 ment is lowered into deep water, its principal axis takes the direction of the 

 current, while the magnet settles itself in the magnetic meridian. After the 

 magnet and the instrument have taken up their respective positions, the 

 clockwork suddenly fixes the magnet at a known time. The instrument is 

 then drawn up out of the water and opened, when the fixed magnet shows 

 the direction, or bearing, of the current below. 



This bearing is shown directly by the instrument when it is suspended from 

 a fixed platform, or from a ship at anchor, or otherwise at rest: When the 

 ship is in motion the instrument is to be used in combination with the deep 

 sea current meter, by which means the velocity and direction of the submarine 

 current can be determined simultaneously by a simple geometrical con- 

 struction. 



409c. Recorder for Indicating Speed, Pressure, &c. 



W. H. Bailey and Co. 



B. ANEMOMETERS. 



408. Anemometer, without frictional parts, suited to measure 

 the speed of air or gases, even when highly heated, or when 

 contaminated with smoke or corrosive vapours. Used by H.M. 

 Inspectors of Alkali Works. Alfred E. Fletcher, Liverpool. 



41O. Lowne's Portable Air Meter, originally introduced 

 by Casella. JR. M. Lowne. 



The indications of this instrument are obtained by means of a light fan 

 which communicates motion to indicating wheels ; the dial of the instrument 

 is placed at right angles to the fan, and is supported by three pillars on a base, 

 which also carries the tube containing the fan. The works are extremely 

 sensitive, the first centres running in jewels, and the indicating parts can be 

 thrown in or out of gear with the fan. 



41Oa. Lowne's Patent Magnetic Air Meter, especially 

 adapted for measuring currents of air, gases, and fluids in positions 

 where delicate instruments would be subject to corrosion. 



R. M. Lowne. 



The peculiarity of this instrument is, that the registering works are en- 

 closed in an air-tight chamber, the connexion of the revolving fans with the 

 works being made through a sheet of brass by magnetism. The fans carry a 

 small bar magnet, and the first wheel of the indicating mechanism carries a 

 piece of soft iron, so that when the fans revolve outside the plate of brass the 

 soft iron revolves within by attraction and thereby moves the works. 



41Ob. Lowne's Patent Colliery Air Meter, constructed 

 expressly for use in mines. R. M. Lowne. 



The external aspect and form of this instrument is that of the well known 

 " Biram's Anemometer." The improvements consist of. 1st, a strong, light, 

 ;aud anti-corrosive fan ; 2nd, a large clear dial ; 3rd, the indicating parts ~are 

 perfectly protected from dust and smoke ; and 4th, a lever is placed in a con- 

 venient position to enable the observer to throw the indicating wheels in or 

 out of gear with the fan. 



