230 METEOROLOGICAL OBSERVATIONS IN OPEN FIELDS, ETC. 



The lowest means observed were, — in 18G9, 2G ; in 1870, 13 ; in 1871, 

 17; in 1872, 23; in 1873, 20; in 1874, 19 ; in 1875, 24, and in 1876, 21. 



These records are introduced for the purpose of showing the general 

 eflects of temperature and the seasons upon the amount of absolute and 

 relative moisture in the atmosphere. It will be observed that at the 

 three stations presented, there is a general resemblance, the differences 

 being perhaps in some degree due to local causes. When represented 

 in a diagram the absolute moisture to be greater and the maximum 

 later at Lansing than at either of the other two stations, at which the 

 amount and range, very nearly coincide, the relative humidity, at all 

 the stations, reaches its minimum in May, is nearly uniform iu the sum- 

 mer months, and is greatest in December and January. 



Absolute Hamidity throusrh thR several months 

 of the year at three American atatious. 



Eelattve Hamiflity tlironffh the several montha 

 of the year at three American stations. 



COMPAJJATIVE IMETEOUGLOGTCAL OESERVATIONS IN THE FORESTS AND 

 IN THE OPEN FIELDS. 



Bavaria. 



In 1868 the Eoyal Ministry of Finances in Bavaria directed the estab- 

 lishment of several meteorological stations, at each of which two series 

 of observations were to be made : one in the open fields, exposed to all 

 the influences of sun and winds, and the other within the shelter of the 

 woods. Care was taken that the conditions of exposure should be as 

 nearly alike as possible, so that the influences of the forests might be 

 fully known. The observations iu the open fields embraced records of 

 temperature iu the sun and in the shade, with common and self-register- 

 ing thermometers; the absolute and relative moisture of the air; ozone; 

 the temperature of the soil at the surface and at depths of ^, 1, 2, 3, and 

 4 feet ; depth of rain and snow ; evaporation from a free water-surface, 

 and from soil saturated by capillary attraction, and the percolation of 

 water through soils 1, 2, and 4 feet deep. In the woods, besides these, 

 the temperature and ozone of the air at the tree-tops, the temperature 

 of trees, and the effect of litter of leaves, &c., upon the soil were made 



