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The Anemometer of Osier, which is that employed in the 

 Dublin Magnetic-Ill and Meteorological Observatory, regis- 

 ters, as is welf known, both the direction and the ■pressure of 

 the w'ind at every instant. The improvements which Mr. 

 Osier has lately introduced into the construction of the instru- 

 ment seem to leave nothing to be desired, so far as relates to 

 the former part of its office. The place of the directing vane is 

 now supplied by a vertical wheel with oblique vanes, which, 

 by the intervention of wheel-work, is made to work round 

 upon a fixed horizontal toothed wheel, and thus to maintain 

 itself always in the vertical plane passing through the direc- 

 tion of the wind. This plan, which is that of the small direct- 

 ing wheel of the ordinary wind-mill, is found to answer its 

 purpose admirably, and to avoid altogether the inconvenience 

 which arose from the oscillations of the vane in the old con- 

 struction. The only change which Dr. Lloyd has adopted 

 in this part of the instrument, consists in placing this wheel 

 centrally, instead of excentrically, with respect to the whole 

 apparatus. 



In the portion of the instrument destined to measure and 

 register the pressure of the wind, which had always been 

 found the least satisfactory. Dr. Lloyd employs a smaller 

 vane-wheel, connected with the former by means of the frame- 

 work of the instrument, and maintained by it always per- 

 pendicular to the direction of the wind. The pressure of 

 the wind acts, through this wheel, upon a spiral spring coiled 

 in a box, the vane-wheel and the spring being connected by 

 an intermediate wheel and pinion. The axle of the vane-wheel 

 carries an endless screw, which works upon a toothed wheel ; 

 and upon an arbor, attached to the axle of the latter, is coiled 

 the chain which communicates with the registering apparatus 

 below. The chain is kept tended, when the pressure of the 

 wind is relaxed, by means of a small spring attached to the 

 registering table. 



The objects proposed to be attained by this arrangement 



VOL. III. y 



