Public Parks. 47 



in the Hudson's Bay region, amid the stillness of the forest, day after 

 day, pursues his accustomed round with the thermometer many 

 degrees below zero, with little or no inconvenience ; and so, too, 

 with the lumberman in the pineries of Maine and Wisconsin. The 

 human system is constantly giving out a volume of heat, which is 

 abstracted more readily by the movement of the air than by mere 

 radiation into space. This deprivation of carbonaceous matter, and 

 the chilling and exhausting effect incident thereto, is but too well 

 known and appreciated by the prairie traveler in winter. The same 

 effect is apparent in operating a locomotive during very cold or 

 windy weather, as it is found much easier to keep up steam while the 

 engine is passing through woods than over the wind-swept ground, 

 although the thermometer may indicate the same temperature. As 

 soon as the train emerges from the shelter of the trees, the steam- 

 gauge falls, and a more liberal supply of fuel is necessary to bring 

 it up again.* 



" Observation shows," says Meguscher, " that the wood of a 

 living tree maintains a temperature of from 54° to 56^ Fah., when 

 the temperature stands from 37° to 47° Fah. above zero, and that 

 the internal warmth does not rise and fall in proportion to that of the 

 atmosphere. So long as the latter is below 67'^ Fah., that of the 

 tree is always highest, but if the temperature of the air rises to 67*^ 

 Fah., that of the vegetable growth is the lowest. Since, then, trees 

 maintain at all seasons a constant mean temperature of 54*^ Fah., it 

 is easy to see why the air in contact with the forest must be warmer 

 in winter, and cooler in summer, than in situations where it is 

 deprived of that influence." f 



While engaged in investigating the nature of ozone, during the 

 winters of 1851 and 1S52, at Burlington, Iowa, I found that there 

 was a difference of temperature between the western or Iowa bank 

 of the Mississippi, (the wind was from the west, and the river frozen 

 at the time,) and the eastern or Illinois side, of 2"", and penetrating 

 the heavy forest that covered the bottom at that time, I found the 

 temperature rising, initil I reached about midway between the river 

 and the prairie, where I found the temperature 16° higher, and it 

 began to lower again upon approaching the edge of the prairie, 

 although the wind was from the west, and, arrived at the prairie, I 

 found the thermometer 4° lower than in the middle of the timber. 



* In applying to the most prominent Railroad Superintendents of this city, their statement is 

 unanimous, that during winter a far greater amount of fuel is consumed by a locomotive running through 

 a prairie region than through one that is densely wooded. 



t Mentoria s-ui Boschi di Lotnhardina. 



