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VII. — Description of an improved Anemometer for registering the Direction of the 

 Wind, and the space which it traverses in given intervals of Time. By the Rev. 

 T. R. Robinson, D.D., Member of the Royal Irish Academy, and of other 

 Scientific Societies. 



Eead June 10, 1850. 



Among the various branches of meteorology, none has been less successfully 

 cultivated than anemometry. As a necessary consequence, we are almost to- 

 tally ignorant of the causes which originate and the laws which govern the 

 currents of the atmosphere, notwithstanding their interesting character as ob- 

 jects of physical research, and their importance as cosmical agents. This, how- 

 ever, is not to be attributed to neglect ; we find Hooke and Derham pursuing 

 the inquiry almost at the first dawn of physical science ; and a variety of 

 subsequent inventions connected with it shew that its importance was never 

 forgotten. But a wrong path of observation was followed: the data which 

 anemology requires are the direction and velocity of the ■wind at a given time; 

 those which (with few exceptions) were sought, are its direction and pressure. 

 Of the many ingenious machines which have been contrived for this purpose, 

 those which are not mere anemoscopes may be reduced to three classes. In 

 the first, originally devised by Hooke, the wind acted on a set of vertical wind- 

 mill-vanes, which are kept facing it by a vane, or some equivalent contrivance, 

 giving them motion round a vertical axis. Tliey turn till the pressure on them 

 equilibrates a graduated resistance of some kind, whose amount measures it. 

 In the second, a square plane receives the impulse of the wind perpendicularly, 

 and thus compresses a spiral spring which is connected with it. This, which 

 was invented about a century ago by the celebrated Bougdee, has been lately 

 brought into general use by Mr. Osslee, who has much improved it, and made 

 VOL. xxn. Y 



