That the stirring or cultivation of the topsoil really does diminish evaporation of water from the soil has been shown by numerous investigations. In 1868, Nessler found that during six weeks of an ordinary German summer a stirred soil lost 510 grams of water per square foot, while the adjoining compacted soil lost 1680 grams,--a saving due to cultivation of nearly 60 per cent. Wagner, testing the correctness of Nessler's work, found, in 1874, that cultivation reduced the evaporation a little more than 60 per cent; Johnson, in 1878, confirmed the truth of the principle on American soils, and Levi Stockbridge, working about the same time, also on American soils, found that cultivation diminished evaporation on a clay soil about 23 per cent, on a sandy loam 55 per cent, and on a heavy loam nearly 13 per cent. All the early work done on this subject was done under humid conditions, and it is only in recent years that confirmation of this important principle has been obtained for the soils of the dry-farm region. Fortier, working under California conditions, determined that cultivation reduced the evaporation from the soil surface over 55 per cent. At the Utah Station similar experiments have shown that the saving of soil-moisture by cultivation was 63 per cent for a clay soil, 34 per cent for a coarse sand, and 13 per cent for a clay loam. Further, practical experience has demonstrated time and time again that in cultivation the dry-farmer has a powerful means of preventing evaporation from agricultural soils.