48 Public Parks. 



During the last six weeks, I liave had three daily observations 

 made of the temperature at the western, the middle, and the eastern 

 portions of Wright's Grove, in the northern part of Chicago. I find 

 as a general rule that the difference between the three points depends 

 upon the direction of the wind, and the sudden changes of temperature ; 

 the middle point being less affected, and ranging from one to seven 

 degrees higher than either of the others. Some days there was no 

 change perceptible in the three points, depending upon temperature 

 and the activity of the wind. The period over which the observa- 

 tions extend has been remarkably mild, and one in which no sudden 

 or great changes have taken place. 



In comparing these observations with others made near the Ar- 

 tesian Well in the western part of the City, I find that only upon one 

 occasion in a month, was the temperature as low as at the Well, while 

 it ranged from one to nine degrees higher. In the month of Decem- 

 ber the thermometer, at 119 Randolph St.,* indicated 10° below zero ; 

 at the x\rtesian Well, 17 ;t at the Observatory, 14 ;J and at Wright's 

 Grove, 1 2 ; at the same time, the wind being from the south-west. 



Trees and plants exercise a marked influence on the humidity of 

 the air, causing its moisture to be more equally distributed. They 

 also act as excitors or conductors of electricity, § and it is supposed 

 in countries where hail storms are frequent and destructive, that they 

 occur in proportion as the forests have been cleared. || "Electrical 

 action being diminished," says Meguscher, " and the rapid congela- 

 tion of vapoi-s by the abstraction of heat being impeded by the 

 influence of the woods, it is rare that hail or water-spouts are produced 

 within the precincts of a large forest when it is assailed by the 

 tempest." % May not the tornadoes which were so common throughout 

 the North-west several years ago, be owing to our treeless prairies .'' 



Trees may be regarded as climatological land-marks, ** the 

 destruction of which causes changes that may be restored by planting 

 them. It is a well established fact that the climate of the older States 



* J. G. Langguth. 



t Wm. Giles. 



: Prof. Safford. 



§ Pouillet, '''' Annates de Chimie" 



II Le A Ipi die cingono V Italia. 



IT Metnoria stti Boschi, etc. 



** It has been a reproach to the aristocracy of England, that in a country where the agricultural 

 capacity of the soil is so limited, and vvliere population presses so closely on the heels of production, 

 that vast tracts of land suitable for agriculture, should be appropriated to forests and the chase ; but 

 those who make this charge, are little aware of the important part which these forests play in the 

 climatology and health of the British Isles. They do not appreciate that forests make the atmosphere 

 purer, and render the climate more equable, thus protecting them from sudden changes, and diminishing 

 the amount of fuel and clothing necessary to their comfort, 



