April 10, 1896.] 



SCIENCE. 



549 



feet around each trunk. So long as there 

 is no color hut pure white for the sun's rays 

 to work upon its heat is largely latent, but 

 let a stick or straw break the surface and it 

 will melt the snow or ice for several times 

 its diameter on every side and stand alone 

 in a few hours. Precisely the same is true 

 upon a larger scale of every stump and tree 

 in a forest. Following the reappearance of 

 the sun after every storm the process begins, 

 slowly or rapidly according to the tempera- 

 ture, clearing up large patches before that 

 beyond shows signs of a break. This is not 

 theory or hearsay, but actual observation 

 covering a score of years spent in daily con- 

 tact with the subject in all its phases. But 

 it is supported by a theory also. It is a 

 well known fact the temperature in a forest 

 is always several degrees higher than it is 

 on open ground under the same conditions 

 otherwise. A series of observations were 

 made by Cornell University several years 

 ago, and although the belt of woodland was 

 only half a mile long and sixteen rods wide 

 the results were very marked. The trees 

 were oak, maple and chestnut, with some 

 hemlock and pines intermixed with an 

 abundant undergrowth. The thermome- 

 ters were changed and one put in another's 

 place frequently in order to detect possible 

 errors. The reporter sums up as follows : 



" A study of the records will show that 

 the temperature of the wooded belt is some- 

 what higher than that of the open field, 

 amounting to from 2 to 4 degrees on the 

 average ; that fluctuations are less extreme 

 and less rapid, and that gradual changes 

 in the temperature of the field do not 

 affect that of the belt until a day or two 

 later." 



Five different stations were kept open for 

 several months ; one thermometer being 

 placed against the trunk of a large oak tree, 

 near the center of the woods ; one near the 

 same t:ree, but not touching it ; a third on a 

 pole four feet from the ground, ten rods 



from the edge of the woods, and two others 

 in the trunks of trees. A considerably 

 warmer temperature was shown by the 

 instrument suspended from the oak tree, 

 but not touching it, although on several 

 days the one out in the field was exposed to 

 the sunshine, while the others were in the 

 shade all the time. Of course the higher 

 temperature would have a two-fold effect 

 upon a snow bank. The warmer the air, 

 the greater its capacity for holding moisture 

 and, consequently, the greater evaporation, 

 and at the same time its melting power 

 would be enhanced to that extent and the 

 snow set to running away as water. Too 

 little weight is generally given to the fact 

 that the rays of the sun must be broken up 

 in order to release heat. A good example 

 is given every spring by John Huntington, 

 who is the owner of the toll road extending 

 from Truckee, California, to Lake Tahoe. 

 The snow shuts this road up very early 

 every winter and a deposit of twenty to 

 thirty feet is nothing unusual. As soon as 

 possible, in the spring, Mr. Huntington 

 sprinkles black dirt on the surface of the 

 snow above where his road is known to be 

 and the effect is wonderful. The layer is 

 not heavy enough to shut out the light from 

 striking the surface of the snow, but it is 

 ample to release the heat rays, and there is 

 a long depression that looks like an artifi- 

 cial excavation in a few hours, and days be- 

 fore the ground is clear on either side the 

 stages are running on bare ground. 



Trees tend to dissipate the snows in 

 springtime also, by breaking up the steady 

 cold winds which come down from the north 

 at that season, almost invariably. When 

 the current is permitted to flow on in unin- 

 terrupted sweep it retains the chill, but let 

 it strike a forest and wind in and out among 

 the trees for a mile or two and there will be 

 a decided change in its temperature. It 

 will be much better prepared to absorb 

 moisture and also to melt the snow banks 



