The Rev. T. R. Robinson's Description of an improved Anemometer. 173 



and the wind three. K degrees on the paper be miles of wind, the number of 

 the former must be 440 x 120 for one of the paper-holder. A train which 

 effects this very simply was arranged for me, by one whose recent loss I lament, 

 not merely from personal regard, but from regret that science is deprived of 

 aid so powerful as that of his high mechanical talents, — the late Mr. Richard 

 Sharp. It is shown in Plate VI., fig. 4, where A is an arbor held loosely in 

 the lower extremity of the axle, and carried round with it by the screw c. An 

 endless screw on this drives the wheel B, of 88 teeth ; a second endless screw S 

 drives C, of 100; its pinion D, of 16, drives E of 96. On this the brass 

 plate P, 14 inches in diameter, is fastened by a steady-pin and the nut H, which 

 also assists in holding down the paper. The speed of the train is therefore 

 = 88 X 100 X 6 = 440 x 120. 



The arrangement for direction is shown in Plate VI., fig. 5. The arbor F 

 (which is also loose in the hollow of the vane axle) bears the wheel G of 96, 

 which drives K of 96. On this the paper-holder P' is seciu-ed by H'; its angular 

 movement is therefore equal to that of the vane, while the paper can be more 

 easily removed than if it were immediately carried by the vane-axle. 



That axle is connected with the arbor F, not by any rigid attachment, but 

 by the spiral spring L. This is necessary, not merely to prevent the destruc- 

 tion of the machinery in violent oscillations of the vanes, but still more to 

 lessen their extent on the register-paper. Though Dr. Whewell had pointed 

 out the magnitude of these oscillations, and the impossibility of preventing 

 them, I was not at all prepared for what I found. It may be that these 

 waverings of the wind are of greater amount at Armagh than elsewhere, owing 

 to the exposed situation, and the undulating surface of the country; but, with- 

 out some contrivance to check them, the direction-papers would be very un- 

 sightly objects. It must, however, be remembered, that they cannot be avoided 

 entirely, nor is it desirable that they should be too much diminished ; for I find 

 that this is a distinctive character of some winds, independent of their velocity, 

 and, therefore, implying some peculiarity in the origin or progress of the cur- 

 rent. In particular I have remarked, that when excessive, it is connected with 

 a roaring sound, that gives an exaggerated impression of their force. This was 

 strikingly exemplified in the destructive tempest of February last, whose highest 

 velocity did not exceed 40 miles per hour. On another occasion, when the 



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