This method of irrigation seems to have been invented independently in several parts of the world. Unfortunately it has been used but little in any of them until this century.
1. It was invented at an unknown time by the Arabs of North Africa. These people still build banks around their olive trees so that no rainfall will escape. Sometimes they let a rill from a nearby hill run into the catchment basin.
2. Something of the same sort was invented by the late Colonel Freeman Thorpe of Hubert, Minnesota, who reported that it made Minnesota's black oaks grow twice as fast as their nearby neighbors that had missed the benefit of such watering.
3. A hole catching water and irrigating trees was devised by the late Dr. Meyer of Lancaster County, Pennsylvania. He had a gully in his orchard. He put a dam of trash across it. Water collected behind this dam. The doctor observed that the trees near it grew better than the rest. This caused him to keep men at work in odd times digging holes near his apple trees. The trees prospered and Dr. Meyer thought that it was profitable.
4. A horizontal terrace holding rainfalls to irrigate trees was invented by Mr. Lawrence Lee, a graduate engineer and orchardist of Leesburg, Virginia. On his steep Piedmont clay hills, he says, "nine-tenths of the water of a summer thunder shower runs away." Aiming to reduce this, he put rows of apple trees across the hill at equal distances apart. He laid off one row on the absolute level. The others were thirty feet apart up or down the hill from this base row. As a result every furrow along the row planted on the absolute contour held water, whereas it drained away from the others because they sloped a little. In a few years Mr. Lee observed that the trees of the contour row which had the water lying above the trees at every rain were distinctly the largest in the orchard.
He took the hint. He planted another orchard where every row was on the contour, the exact level. Then he used a Martin
