On the Motions of the Tendrils of Plants. 345 



Respecting the equality of the teeth of your dividing 

 machine, whatever error there may be before the shifting 

 of the moveable ring, it is clear, the same must exist in 

 them both, being in contact and cut together at the same 

 time. After being reversed and worked round with the cut- 

 ter a few times, which will produce opposite teeth all the 

 way round, as stated in mv last, the next move must be 

 one quarter, or 90°, and this leads ine to the grand pointlat 

 once. I will now suppose that there is some considerable 

 error, however. In this situation there will be found four 

 teeth, and no more, in perfect coincidence and in their 

 true place, on the upper and lower ring, at the four quar- 

 ters, and bv this move it is clear that the largest teeth are 

 placed so as to meet the smallest on the opposite ring. Con- 

 sequently, when the cutter is turned round, its whole ten- 

 dency vvili be to equalize the teeth, which are now under 

 the reciprocal control of each other, so that, by shifting and 

 racking a few times more, this business will be finished to 

 the greatest degree of exactness : the proof of which is 

 simple and easy, it lies in the machine itself, which is, 

 after the cutter is taken away, to move the ring 90°, and 

 then examine the comcidence in every part, which from 

 the nature of the process, I have no duubt, will be found 

 perfectly correct. If ocular demonstration will satisfy, 

 here it mav be had. 



■ In all that I have said on this subject, my aim has been 

 rot elegance of style, but plainness and precision ; — and 

 I think, '.vhoever cannot understand it so far as to enable 

 him t(i nifike such a machine, would be unfit to undertake 

 it on otlier accounts. 



I am, sir. 



Yours truly, 



'l-ittle Mary-Ie-Bone Street, JOHN SxANCLIPFE, 



Nov. 19 1812. 



LXII. On the Afntions of the Tendrils of Plants. By 

 Thom4s An'drew Knight, Esq. F.R.S. In a Letter to 

 the Right Hon. Sir Joseph Banks, Bart. K.B.P.R.S.* 



Mv DKAR Sir, 1 he motions of the tendrils of plants, 

 and the ctforis they app-irently make to approach and 

 at';ich ihemsrives to contiguous objects, have been sup- 

 p>M{i by nianv nainralifts I0 orii'inate in some degrees of 

 gensaiion and pciccpiion : and though other naturalists 



' From the Pliiiot>ophical Transaclious fur 1812, part ii. 



have 



