48 KANSAS ACADEMY OF SCIENCE. 



year a great change took place which has, for generations at least, dispelled all 

 fears of further encroachments, and which may eventually make of old Doniphan 

 something of a pleasure resort. 



By the map, it will be seen that as the river came southward it made a sharp turn 

 toward the west, at A, dividing into two branches which soon united, encircling 

 what was known as "The Island" (/). The last June rise was unusual for this lo- 

 cality, and the upper branch of the river soon broke over the "point," at B, thus 

 forming the first cut-off. But it was not long until the lower portion overflowed the 

 bottoms directly south of it, taking a straight course across the neck and joining 

 the main channel below. Thus, two additional islands, C and D, were formed, and 

 the old channel to the north of them remained filled with water and constituting 

 the so-called lake. This lake is about four miles in length and, in places, a half to 

 three-fourths of a mile wide. A number of soundings, taken October 9, showed 

 depths varying from 10 to 18 feet. Deposits of sand and mud have about closed up 

 both ends of the lake, but the southern end can never become completely closed, as 

 Independence creek enters about a mile from this end, and will furnish more or less 

 current, especially in time of freshet, thus tending to keep the channel open. 



SELECTIVE ABSORTION OF HEAT BY LEAVES. 



BY A. G. MAYEE, LAWKENOE. 



In this research, it was necessary that the thermopile measure with precision 

 down to thousanths of degrees of temperature; it was, therefore, important to cut 

 ofiE all air currents. 



The thermopile was incased in two tin boxes, the one outside the other, leaving 

 an air space inclosed by tin all around the instrument; a suitable opening, which 

 could be closed at will with a screen impervious to radiant heat, allowed the heat to 

 fall directly upon the thermopile when desired. 



By allowing heat from any source to fall directly upon the thermopile, and then 

 obliging it to pass through a leaf placed in its path, it became possible to determine 

 the effect of the leaf upon the radiant heat. 



Experiments were made upon a great many leaves and petals of flowers, and the 

 results were surprisingly alike. As an example, we will cite the case of elm leaves. 

 A single elm leaf in the path of the heat allows only 23.5 per cent, of the radiant 

 heat to pass through it; so 76..5 per cent, is absorbed by the leaf. If now the heat, 

 which has already passed through one leaf, be allowed to pass through a second, we 

 find that the second absorbs only 21.4 per cent, and transmits 78.6 per cent., show- 

 ing plainly a remarkable selective absorption. A third leaf in the path allows 83 

 per cent, of the heat which passed through the second leaf to pass through unab- 

 sorbed. The transmitting powers of leaves varies from 17.6 to 28.3 per cent. The 

 lower number is for the thick leaves of the muUen, and the higher represents the 

 transmitting power of rose leaves. The transmitting power of various flower petals 

 was as follows: Red rose, 31.2 to 33.3 per cent.; yellow rose, 23.9 per cent.; white 

 rose, 26.6 per cent.; white petals of (Jinothera speciosa, 26.6 per cent.; petals of 

 purple grass, 30.8 per cent. 



Leaves are, therefore, good absorbers of heat, but bodies which are good ab- 

 sorbers are good radiators. The radiation from leaves is about 78, lampblack being 

 100. We see, then, that were the leaves to radiate their heat at night at this rapid 

 rate they would soon lose much of the energy which they received from the sun dur- 



