368 Mr. Redfield's Reply to Dr. Hare, 



" matter " or " fluid mass " will not quicken as it approaches 

 the centre, unless as resulting from a centripetal force " caused 

 by suction at the axis." (31-32, Amer. Journ. xlii. p. 146.) 



A constant centripetal force I have already recognised on 

 this as well as former occasions. But this by no means re- 

 quires or produces a direct centripetal course in the moving 

 air which yields to its influence. But in the cause assigned 

 for this force, as well as in the specific directions of the move- 

 ments produced, we differ essentially. So far from ascribing 

 this quickened gyration to the "suction" alleged by Dr. Hare, 

 I know of no such power in the uninclosed atmosphere, con- 

 ceiving that neither rarefaction nor any other known cause 

 can here occasion " suction," according to the common use of 

 this term. Air, whether rarefied or not, can never ascend but 

 in obedience to a pressure or force, sufficient to exceed both 

 its own weight and that of all the atmosphere which lies im- 

 mediately above it, or in the immediate direction or locality 

 of its motion. This erroneous hypothesis of '' suction," in 

 some form or other, appears to lie at the bottom of the various 

 speculations and inductions of my opponents. 



In noticing the spirally involute and quickening motion 

 which I allege as observable in " all narrow and violent vor- 

 tices," Dr. Hare gives in the American Journal an erroneous 

 reference for his quotation ; and the latter seems also to be 

 somewhat inaccurate. I do not see that his speculations on 

 this quickened motion " towards the centre or axis of the 

 whirl*'," can affect either my views or the disputed fact of gy- 

 ration ; and they are sufficiently answered by observations 

 published in my first paper j-, as well as by the remarks made 

 above on centripetal force. 



Dr. Hare thinks that so far as my observations show the 

 quickening of the whirling motion towards the centre of the 

 tornado, they tend to confirm the views of my opponents and 

 to refute those which I uphold. To me it appears that this 

 is an entire abandonment of his ground. It is the general 

 fact of gyration which I am chiefly concerned to uphold, and 

 which has been combated by him and his predecessor in this 

 controversy,. I dispute with no one as to how it may be pro- 

 duced. Should better explanations of this fact than mine be 

 offered, they will be cheerfully adopted. In the mean time, 

 I shall adhere to my observations and opinions, rather than 

 to the hypotheses and speculations of my opponents. 



Dr. Hare thinks it will be conceded, " that any theory of 



* Not "the centre of the axis of the whirl," as erroneously quoted by 

 Dr. Hare, 

 f Silliman's Journal, vol. xx, pp. 45-46. 



