334 The Rev. Patrick Keith's Reply to Mr. Meikle. [Nov. 



petal force only, it v. ill then fly off in a tangent, as the experi- 

 ment of a stone fairly thrown from a sling will show. 



I have said that the radicles ought to have been elongated in 

 the direction of a tangent ; but the relief wanted had partially 

 taken place, at least upon Mr. Knight's principles. For Mr. 

 Knight says, that in the case of the vertical wheel performing 

 150 revolutions in a minute the influence of gravitation was 

 conceived to be wholly suspended, and consequently the centri- 

 petal force. The radicles were, therefore, subjected to the 

 agency of the centrifugal force alone ; and though they would 

 still have been compelled to revolve in a circle, from their indis- 

 soluble connexion with the wheel ; yet as Mr. Knight regards 

 the matter which is added to the apex or point of the radicle as 

 " being fluid, or changing from a fluid to a solid state," and 

 hence sufficiently susceptible' to the influence of gravitation to 

 give it an inclination dowuwards, when lying at rest in the earth, 

 I thought I might assume the same fluidity in the case of the 

 beans attached to the wheel, and contend that similar causes 

 should produce similar effects ; or, that the continual tendency 

 of the beans to fly off in a tangent ought to have made the fliftd 

 particles that were successively added to the points of their 

 sjerminatinu; radicles to assume the direction of a tangent also. 

 But this notion I hai'e, perhaps, carried rather too far. 



There is a curious consequence that would result from Mr. 

 Knight's doctrine, if true, vhich has just occurred to me. If 

 gravitation is the true cause by which the roots of plants are 

 made to descend, and their stems to ascend ; and if the result of 

 Mr. Knight's experiments is to be regarded as a proof of the 

 fact ; then, if the diurnal or rotatory motion of the earth were to 

 be but sufficiently accelerated, the roots of trees would grow 

 upwards, and the stems downwards, the earth acting the part of 

 the upright and revolviug wheel. 



Spectatum admissi risum teneatis amid ?— 



I have but little more to add in reply to Mr. Meikle's remarks, 

 in which I cannot but admit that he has given us a very conspi- 

 cuous display of his knowledge of the principles of mechanics, 

 and acquaintance with the laws of motion, and composition of 

 forces ; but unfortunately he has done nothing to clear up the 

 obscurity of the point in question, or to help us out of our diffi- 

 culties on either side. In short, he has left us precisely where 

 we were before. For allowing that his strictures on my paper 

 were even well founded, stil! they affect but a mere flaw — a mere 

 trifle — a mere speck in the colouring, that tends nothing to the 

 prejudice of the main arguments which I adduce. The me- 

 rits of my paper caa be estimated only by a minute examination 

 of the phytological facts which it exhibits, and of the legiti- 

 macy of the conclusion which I have thought myself entitled to 



