It is obvious, that in so far as the roots of the turnip, the carrot, and the potatoe, consist of water, they can serve the purposes of drink only--they cannot feed the animals to which they are given. Now, the quantity of water in the turnip is so great, that 100 _tons sometimes contain only nine tons of dry feeding matter_--more than nine-tenths of their weight consisting of water. But again, their constitution is so variable, that 100 _tons sometimes contain more than twenty tons of dry food_--or less than four-fifths of their weight of water. It is possible, therefore, that one acre of turnips, on which only twenty tons are growing, may feed as many sheep as another on which forty tons are produced. 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. [4] [Footnote 4: For our authority on this subject, we refer to Johnston's _Suggestion for Experiments in Practical Agriculture_, No. 111. pp. 62 and 64, of which we have been favoured with an early copy by the author.] This latter fact, shows the very slippery ground on which the assertion rests, that has lately astonished the weak minds of our Southern cattle-feeding brethren, from the mouth of one of their talented but hasty lecturers--that the potatoe contains two or three times the weight of nourishment which exists in the turnip. It is true that _some_ varieties of potatoes contain three times as much as _some_ varieties of turnip--but, on the other hand, some turnips contain as much nourishment as an equal weight of potatoes. But no man can tell, by bare inspection, as yet, to which class of turnips, the more or less watery, his own may belong--whether that which is apparently the most prolific may not in reality be the least so--whether that mode of manuring his land which gives him the greatest weight of raw roots may not give him the smallest weight of real substantial food for his stock. What a wide field, therefore, for experiment? To what useful results might they not be expected to lead? If any of our readers wish to undertake such experiments, or to learn how they are to be performed, we refer them to the pamphlet mentioned in the note.