text:  What therefore can be more uncertain than the feeding value of an acre of turnips as estimated by the weight? How much in the dark are buyers and sellers of this root? What wonder is there that different writers should estimate so very differently the weight of turnips which ought to be given for the purpose of sustaining the condition or of increasing the weight of the several varieties of stock? Other roots exhibit similar differences; and even the potatoe while it sometimes contains thirty tons of food in every hundred of raw roots at others contains no more than twenty--the same weight namely which exists at times in the turnip