160 REPORT —1840. 
any shake. The pencil and descending nut in fig. 3 work about 
this fixed barrel by means of two supports EH, figs. 2, 3 
and 9 attached above to the under part of the plate A, and 
below to a horizontal clasp of brass P P, figs. 3 and 9. The 
clasp freely encircles the barrel when closed, and has small 
friction wheels W W W, fig. 9, inserted in it; the extremity 
or point of the screw M, figs. 3 and 9, moved by the wind- 
mill, turns upon this clasp, as at P, fig. 9: this clasp is 
shown in this figure open, by means of the joints at P P. This 
arrangement enables the observer when the pencil has descended 
for any given time, to remove the fixed barrel D and substitute 
a similar one, on which the register is continued, whilst that 
just removed is read off and transferred at the observer’s leisure 
and convenience. ‘The process of tabulation becomes in this 
way avery simple affair. The removal of the barrel and re- 
placing of the pencil at the top of the scale is easily effected. 
The nut N, figs. 3 and 5, is first removed and the screw within 
withdrawn; the brass ring H, fig. 7, is then unscrewed by 
inserting the points of the bent lever L, fig. 8, into the small 
holes of the ring seen in figs. 7, 3, and 12. Finally the barrel 
is withdrawn from off the axis and another substituted as al- 
ready described. 
The mechanism of the pencil is represented in fig. 10. In this 
figure M represents the nut traversing the screw SS. This nut 
is made in two parts and is held together by a steadying pin u 
and a clamp screw C. One of the standards of support E, figs. 
3 and 10, passes between this clasp and the steadying pin, by 
which the pencil is faithfully steadied in the course of its de- 
scent along the cylinder. There isa small projecting arm on 
one side of the nut, to which is attached by means of a centre 
pin a curved piece 0; this piece is moveable about the pin car- 
rying within the curve a small knob of brass uv set within the 
curve on an axisa. The pencil p and balance weight q are 
attached to this knob v, and thus the pencil is gently pressed 
against the cylinder as shown in fig. 3. The lower part of the 
thread of the vertical rod s on which the nut travels is left 
plain and smaller than the screw above, as seen at P, fig. 9, in 
order to allow the nut to fall freely off ; hence if the instrument 
has run out at any time before attention is again given to it, da- 
mage to the fly and wheel work above, by the resistance which 
would otherwise ensue, is prevented. When the barrel has been 
replaced we have merely to turn back the screw C, fig. 10, and 
run the whole up to the head of the cylinder: again clamp the 
nut, and the Anemometer continues to register on the barrel as 
before. 
In order to measure and transfer the amount of wind, there is 
