ON THE ANEMOMETERS OP PLYMOITTH. 



257 



before obtained; these are given in Table XV. From these we deduce the 

 eiglit effective forces in velocity and direction, for each of the years 1841 

 and 1842, as follows. 



Greenwich Observations. 



These values, when laid off as before, figs. 15 and 16, Plate XXXVIII., 

 give the following results. 



Results of Osier's Anemometer at Greenwich, 



There is evidently a general agreement in the results of the Devonport 

 and Greenwich observations, the mean direction of the wind being nearly the 

 same, and the rate of motion of the air not very different ; for it is to be 

 considered that the Greenwich observations fou 184<l only include a period 

 of eleven months, whilst the approximative mean force has been deduced 

 from a register of pressures not under a quarter of a pound ; still the results 

 are so far satisfactory as tending to show the same general course of the air 

 in the annual movement in these latitudes, and which is evidently between 

 the north and east, and at a mean rate of from four to five miles per hour, 

 being about the same rate of motion as that deduced by the anemometers at 

 Plymouth for the same years, a coincidence not unworthy of remark. There 

 is likewise a very general agreement in the characters of the diagrams of the 

 winds for these years, Plate XXXVIII. In both instances the year 1 842 

 presents a less result than 1841, and the figures representing these winds at 

 Devonport and Greenwich have a very similar relation. I cannot therefore 

 but believe, that with perfect instruments of this kind, most valuable infor- 

 mation would be obtained in this department of meteorology. 



The registers of Osier's anemometer are still under investigation, and will 

 be further reported on. I am enabled however to give in this report the 

 relative velocity and amount of wind to eight points of the compass, in con- 

 nexion with the atmospheric temperature and pressure and amount of rain for 

 the two years just given, and which appears to be as in the following Table. 



Points of Direction. 



N. 



N.E. 



S. 



w. 



N.W. 



Mean pressure 



Velocity in miles per hour 



Total hours 



Integral effect 



Barometer to 32° 



Temperature 



Rain in inches 



1-65 



18-3 



727 

 13304 

 29-875 

 47-92 



1-303 



1-68 

 18-47 



501 

 9253 

 29-880 

 46-97 

 0-294 



2-37 



21-7 



707 

 15342 

 29-816 

 50-66 



1-404 



2-02 

 20-28 



995 

 20178 

 29-798 

 51-68 

 4-647 



2-77 

 23-75 



1112 

 26410 

 29-642 



3-09 

 25 



1040 

 26000 

 29-717 



54-39 j 52-68 

 7-987 6-218 



206 

 20-46 

 1004 

 20541 

 29-751 



51-5 

 2-950 



3-3 



25-9 

 1641 

 42501 

 29-891 

 51 

 1-544 



1844. 



