C 18 1 



not, for example, feem very unnatural for a perfon who 

 had made only one of thefe experiments, to concludeyhwz 

 analogy, that the refult in the fomewhat fimilar cafe, which 

 he had not tried, would be fimilar to that which he had 

 tried : yet it appears, that with regard to grain (that kind 

 of it at leaft which had been proved) a difference in the 

 weight of feed, if it has any effecl: on the future crop at all, 

 is fo little as fcarcely to be perceptible ; whereas, with re- 

 fpecl: to the plants of potatoes, it is fo great as to augment 

 or diminifh the total amount of the crop in the ratio of 

 nine to one. This, at the fame time that it fhould teach 

 the farmer to be extremely cautious how he fuffers his 

 mind to be influenced by vague reafoning, ought ftrongly 

 to incite him to redouble his attention, and by well-chofen 

 experiments endeavour to obtain fome kind of certainty in 

 the knowledge of many particulars, wherever he finds that 

 his opinions have been adopted in confequence of early 

 prejudices, or crude indigefted notions arifing from theories 

 that have not been fufficiently underftood. 



§. v. 



But although it appears, from experiments firft, 

 Jecondy and third, fufficiently obvious, that the crop 

 of potatoes is augmented by the weight of feed, yet 

 it alfo appears from experiments fecond and thirds 

 that the weight of produce is not augmented in the 

 fame proportion with the weight of the feed: for al- 

 though the weightier!: feeds have always yielded the 

 weightiest crop in proportion to the extent of ground, 

 yet the lighteft feeds have as invariably produced the 

 greateft return in proportion to the weight of feed 



planted. 





