27. Definition of the habitat 18 28. Factors 18 Classification of Factors 29. The nature of factors 19 30. The influence of factors 19 Determination of Factors 31. The need of exact measurement 20 32. The value of meteorological methods 20 33. Habitat determination 21 34. Determinable and efficient differences 21 Instrumentation 35. Methods 22 36. Method of simple instruments 22 37. Method of automatic instruments 23 38. Combined methods 23 CONSTRUCTION AND USE OF INSTRUMENTS 39. The selection of instruments 24 Water-content 40. Value of different instruments 25 Geotome methods 41. The geotome 25 42. Soil borers 26 43. Taking samples of soil 26 44. Weighing 27 45. Computation 28 46. Time and location of readings 28 47. Location of readings 29 48. Depth of samples 30 49. Check and control instruments 30 Physical and Physiological Water 50. The availability of soil water 30 51. Terms 31 52. Chresard determination under control 32 53. Chresard readings in the field 33 54. Chresard values of different soils 34 Records and Results 55. The field record 35 56. The permanent record 36 57. Sums and means 36 58. Curves 37 Humidity 59. Instruments 37 Psychrometers 60. Kinds 37 61. The sling psychrometer 38 62. Readings 39 63. Cog psychrometer 39 64.