GERMAN METHODS. 39 



For this purpose observations could best be taken in tlie central prov- 

 inces and Berar, as tbey are hottest in April and May and the forests 

 are extensive. India also permits a study of the effects of irrigation, 

 on forests. 



The German service supj)lies each of its stations with psychrome- 

 ter, maximum and minimum thermometers, six soil thermometers, ba- 

 rometer, evaporometer, and rain gauge. The soil thermometers for the 

 surface and the depth of inches are supported by small tripods. The 

 four thermometers for greater depths are in wooden cases, open at the 

 bottom and extending downwartl only so far that the bulb of the ther- 

 mometer may remain in contact with the soil at the depth required. 

 The cases are placed together and are open at the top to permit of 

 ready access to the instruments. A cover over the open ends keeps 

 out the water and exterior air currents. The thermometers are taken 

 out for observation, read as quickly as possible, and replaced. The 

 evaporometer is a square receptacle of zinc with a surface of about 2 

 square feet and a depth of about 5 inches. A measured amount of 

 water is placed in it, and the loss, expressed in thickness of layer evap- 

 orated, is noted at the beginning of each month. This instrument is 

 protected from iirecii>itation by a wooden roof, but the air is permitted 

 to have free access. The force and direction of the wind are estimated, 

 the former on the 1 to 4 scale. 



The rain gauge has an opening of about 2 square feet (18.58*^"') and 

 is placed at a height of 5 feet (1.52'"), like the other instruments. The 

 snow gauge has the same opening, but a larger body, to prevent the 

 snow from being blown out. 



The observers were intrusted with other observations, esi)ecially 

 those relating to the leating, flowering, and other .stages of certain 

 plants, and the list of plants to be observed is given. It includes 

 26 wild plants, mostly trees and shrubs, and 7 cultivated ones. 

 Observations are required of the arrival and disappearance of a few 

 designat«Hl species of birds and insects, and the time of heat of the 

 deer and rabbit. The order in which observations were to be taken, 

 the mode of recording, the methods of reduction, and all other details 

 are minutely given in the instructions to observers, and j)ainstaking 

 care is required throughout. 



From 1884 Dr. Lorenz-Liburnau put in operation some of the fertile 

 ideas which he had already suggested. The three systems of radial 

 stations were organized as already described. Dr. Liburnau thought 

 that the general cliaracter of the influence of the forest on climato 

 was already determined and that there was now required only the 

 elaboration of details. The radial stations were designed to fix the 

 relations of the forests to the climate of the vicinity with varying direc- 

 tion of wind, and a special series of observations were made to fix the 

 relations of forest humidities and temperatures at various elevations, 

 below, in, and above the tree tops, and to determine their modifications 

 with general changes of the weather. 



