76 THE: HABITAT 
can be miade without serious inconvenience. The reading of the register: 
ing dials requires detailed explanation, and for this the reader is referred 
to the printed directions which accompany the instrument. In setting up 
the anemometer it must be borne in mind that the ecologist desires the wind 
velocity for a particular habitat. In consequence, the precautions which the 
meteorologist takes to place the instrument at a certain height and well 
away from surrounding obstructions do not hold here. Standard anemo- 
meters are furnished by H. J. Green, and J. P. Friez for $25 each.. 
The anemograph is an anemometer electrically connected with an auto- 
matic register. It is the only instrument adapted to continuous weekly 
records in different habitats, but the price, $75 ($25 for the anemometer 
and $50 for the register) is practically prohibitive, at least until a complete 
series of ecographs for other factors has been obtained. 
110. Records. The following form is used as a combined record for 
precipitation and wind: 
i at 
\ : or v ’ | - RAINFALL WIND - 
i / E 8 3 a z % ‘ (2a. |: 
? vi 9 
‘yf Be | BS a ae | ae | g | GS [alge a) fs |e 
(jae ee =) km n <q ; i) a Ay Ime) ran la 
29/8/04| 6:30 P.m.|Half gravel| Hiawatha | 2550 m. N.E/17°| Asterare| 1 Shours|..| 5 |3 ft.) N.W 
31/8/04] 5:45 p.m se ae st m as | Trace / 10 min.}../ 12 | “ ns 
2/9/04| 4:00 P.M. ve ot e a | 2 |2 hours| ff oy w. 
3/9/04)10:00 P.M “ ee a at oe Trace |........]..| 18 | “ pan Pe 
SOIL 
111. Soil asa factor. In determining the value of the soil as a factor in 
a particular habitat, it must be clearly recognized that its importance lies 
solely in the control which it exerts upon water-content and riutrient-con- 
tent. The former is directly connected with the texture or fineness of the 
soil, the latter with its chemical’ nature. Accordingly, the structure of the 
soil and its chemical composition are the fundamental points of attack. 
These are not at all of equal value, however. Water is both a food, and a 
solvent for the nutrient salts of the soil. Furthermore, the per cent of sol- 
uble salts, as determined in mechanical analyses, is practically the same for 
all ordinary soils. Indeed, the variations for the same soil types are as 
great as for entirely different types. For these reasons, soluble salt-con- 
tent may be ignored except where it is readily seen to be excessive, as in 
alkaline soils; and determinations of chemical composition are necessary 
only in those soils which contain salts or acids to an injurious degree, e. g., 
