271 
‘The Anemometer of Osler, which is that employed in the 
| Dublin Magnetical and Meteorological Observatory, regis- 
ters, as is well known, both the direction and the pressure of 
the wind at every instant. The improvements which Mr. 
Osler 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 
j 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 
_ yane-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. 11. Y 
