"I AM interested to know where you learned these things about acid soils and lime and limestone," said Mr. Thornton. "Mostly in the agricultural college," replied Percy, "but much of the information really comes from the investigations that are conducted by the experiment stations. For example, the best information the world affords concerning the comparative value of burned lime and ground limestone is furnished by the Pennsylvania Agricultural Experiment Station. Those experiments have been carried on continuously since 1882, and the results of twenty years' careful investigations have recently been published. A four-year rotation of crops was practiced, including corn, oats, wheat, and hay, the hay being clover and timothy mixed. With every crop the limestone has given better results than the burned lime. In fact the burned lime seems to have produced injurious results of late years, and the analysis of the soil shows that there has been large loss of humus and nitrogen where the burned lime has been used, the actual loss being equivalent to the destruction of more than two tons of farm manure per acre per annum." "Well, we surely need this information," said Mr. Thornton. "I have always supposed that the teachers in the agricultural college knew little or nothing of practical farming." "I did not go to college to learn practical farming, if we mean by that the common practice of agriculture," replied Percy. "I already knew what we call practical farming; that is, how to do the ordinary farm work, including such operations as plowing, planting, cultivating, and harvesting; but it seems to me, Mr. Thornton, that this sort of practical farming has resulted in practical ruin for most of these Eastern lands. The fact is there is a side to agriculture that I knew almost nothing about as a so-called practical farmer, and I am coming to believe that what we commonly call practical farming is often the most impractical farming,--certainly this is true if it ultimately results in depleted and abandoned lands. The truly practical farmer is the man who knows not only how to do, but also what to do and why he does it. The Simplon railroad tunnel connecting Switzerland with Italy is twelve miles long,--the longest in the world. It was dug from the two ends, but under the mountain, six miles from either end, the two holes came together exactly, within a limit of error of less than six inches, and made one continuous tunnel twelve miles long. Now, this was not all accomplished by the practical men who knew how to handle a spade in digging a ditch. The work was controlled by science, and it was known in advance what the results would be. I do not mean that it was known how hard the digging would be, nor how much trouble would be caused by caving or by water; but it was known that if the practical work was done, the final outcome would be successful.