165 



over by the wind in a certain time, i.g, miles in days — ^to 

 tabulate the total amount of air which passes the place of 

 observation. It consists of a set of small wind wheels (like an 

 old-fashioned window ventilator), kept towards the wind by a 

 vane. A vertical motion is communicated to a pencil, which 

 thus records the amount of wind, a certain number of revolu- 

 tions of the wind wheels corresponding to a certain depression 

 of the pencil ; and the circular motion of the same pencil 

 upon the axis of the vane gives the direction of the wind. 



But this anemometer is imperfect, and requires such cor- 

 rections to be made as render it exceedingly difficult of appli- 

 cation. In a brisk wind the noise of the wind wheels is heard 

 at some distance, and there must be a considerable friction- 

 error not yet accounted for. In fact, it is useless for general 

 purposes, and is only valuable for making comparative obser- 

 vations, namely, the velocity of wind here and elsewhere, 

 where similar instruments are erected. It does not give the 

 absolute velocity of the wind at any station. 



Osier's anemometer registers not only the pressure, but the 

 direction of the wind at all times, and is much more complete 

 and exact than that of Whewell. But even it is liable to the 

 charge of imperfection, and the inventor has spent no little 

 time in making improvements. At present it is contemplated 

 to erect an instrument combining the peculiarity of Dr. 

 Robinson's anemometer with his own ; and when completed 

 will be unique. 



The peculiarity of the improvement by Dr. Robinson, of 

 Armagh, who acknowledges the idea to be that of Mr. R. 

 Lovell Edgeworth, is this — " If hemispherical cups be carried 

 by horizontal arms attached to a vertical axis, with their 

 diametrical planes vertical, they constitute an effective wind- 

 mill, which revolves with one-third of the wind's velocity." 



The Presiden r exhibited to the Society a specimen of the 

 lace tree from tlie West Indies; the lacy appearance being 

 produced by macerating the cellular tissue between the 



