════╤═════════════════════════════╤═══════════╤═══════════╤══════════════╤═══════════ │ TEMPERATURE │ LIGHT │ HUMIDITY │WATER-CONTENT │ WIND ────┼─────┬─────┬─────┬─────┬─────┼─────┬─────┼─────┬─────┼──────────────┼─────┬───── TIME│10:40│10:46│10:50│10:55│11:00│12:00│12:05│11:10│11:20│ % │11:30│11:45 A.M.│ │ │ │ │ │ │ │ │ │ │ │ ────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼────┬────┬────┼─────┼───── STA-│1½ m.│Surf.│ 5 │ 10 │ 15 │1½ m.│Surf.│1½ m.│Surf.│ 5 │ 10 │ 15 │1½ m.│Surf. TION│ │ │ │ │ │ │ │ │ │ │ │ │ │ ────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼────┼────┼────┼─────┼───── 1. │16 │25 │ 9.6│8.4 │7.8 │ .08 │ .06 │ 73 │ 81 │24.2│19.2│19.5│ 298│ 0 2. │16.2 │30.5 │ 8.5│8.4 │7.8 │ .11 │ .09 │ 73 │ 86 │22 │22.5│19.4│ 375│ 2 3. │16.2 │17.8 │ 7.6│7.8 │8 │ .08 │ .06 │ 73 │ 95 │22.1│20.4│21.6│ 640│ 6 4. │15.6 │26.2 │ 10.6│8.4 │8.2 │ .06 │ .03 │ 81 │ 95 │25.4│23.1│22.4│ 275│ 12 5. │17.6 │25.4 │ 7.6│7.4 │7.2 │ .03 │ .02 │ 90 │ 95 │27.2│19.8│18.8│ 178│ 2 6. │16.2 │20.2 │ 8.4│7 │6.2 │ .02 │ .01 │ 82 │ 90 │27.6│20.8│18.8│ 115│ 4 7. │15.8 │17.2 │ 6.4│6.4 │6.1 │ .05 │ .04 │ 82 │ 90 │23.8│19 │19.3│ 60│ 0 ────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴────┴────┴────┴─────┴───── METHOD OF ECOGRAPH BATTERIES =136.= A battery of recording instruments consists of a selagraph, a psychrograph, and a thermograph, to which an anemograph is added when possible. As stated before, the determination of water-content by the geotome method is more satisfactory than by any automatic instrument yet devised. When the base station is located where the sunlight is unobstructed, which should be the case whenever possible, it is unnecessary to include a selagraph in those batteries placed in similarly exposed stations, since the light values will be the same. As a rule, batteries are established within different zones or different habitats, except where a highly diversified habitat is made the subject of special inquiry. Such a restriction arises from the fact that expense, care of operation, etc., place a limit upon the number of batteries, and, in such case, the task of primary importance is to establish the physical character of representative habitats. For these reasons, the first series of thermographs established in 1903 was located with respect to altitude, the instruments being placed at Manitou 2,000 m., Minnehaha, 2,600 m., and Mount Garfield 3,800 m. In 1904, the stations established for the record of temperature and humidity were situated with respect to habitats representing the four formations: gravel slide, half gravel slide, spruce forest, and brook bank.