158 REPORT—1840. 
very recently succeeded in correcting the defects attendant on 
the working of the machine generally. 
The recent improvements, in effecting which the sum of 10/. 
granted by the Association at its last Meeting at Birmingham 
has been expended, I now propose to describe; and as no par- 
ticular description of the Anemometer by drawings has ever yet 
appeared in the Reports of the Association, it may not be amiss 
to give an account of the whole as it now works, since I cannot 
but think it entitled to considerable attention, and that it must 
eventually come into general use in Meteorology. 
For the carrying on these recent improvements, the scien- 
tific world is indebted to Mr. Kerr of this town, on whose house 
the machine is now at work, and who has kindly undertaken to 
attend to the Register. 
Plate I. AAA, figs. 1 and 2.—is a circular metallic plate, move- 
able about an axis D, by the action of the wind on a vane V, fig. 
2. A small windmill fly W, formed of brass planes and turned at 
an angle of 5 degrees with a plane perpendicular to the direction 
of the wind is fixed on this plate. The fly revolves by the action 
of the wind, against which it is kept by the vane V, and gives 
motion to an endless screw @; this screw operating on a verti- 
cal wheel 4 gives motion to a horizontal wheel d, through the 
intervention of a second endless screw, not seen in the figure, 
and placed on its axis. This last wheel ¢ is placed at the ex- 
tremity of a long vertical axis M, figs. 1 and 2, upon this is cut 
the thread of a fine screw carrying a nut M, figs. 3 and 10. 
The nut M supports a pencil p, figs. 10 and 3, which acts by 
means of a balance weight g against a fixed cylindrical barrel 
D, fig. 3. The vertical axis of the plate A moves by the action 
of the wind on the vane V through the centre of this barrel, as 
in fig. 1, and thus by the revolution of the fly, and the action of 
the vane in turning round the plate, the pencil is caused to de- 
scend and tracea line on various parts of the cylinder D, fig. 3. 
There are 16 vertical lines painted on the barrel, corresponding 
to 16 points of the compass, as in figs. 3 and 12; hence, whilst the 
vane V by turning the plate A causes the pencil to apply itself 
to that line coincident with the direction of the wind, the wind- 
mill W causes it to descend and trace a line proportionate to 
its velocity for a given time—the motion of the fly being by the 
toothed wheels and screws fig. 1, so reduced, that for 10,000 
revolutions, the pencil only descends ;4,th of aninch. The 
barrel D is varnished white, and readily receives the trace of the 
pencil in a thick irregular line, the middle of which indicates 
the mean direction and velocity of the wind. 
When the pencil has descended to the bottom, it must be 
