294 
Journal of Agricultural Research 
Vol. XIV, No 8 
from 35 to 85 per cent. The writer hopes, with certain additions to the 
room, to make it possible to regulate the humidity at any point between 
10 and 90 per cent. 
This humidity room has been in constant operation for over seven 
months, and has proved very satisfactory. It is possible to get a more 
elaborate equipment and no doubt a more satisfactory one for a larger 
room, such, for example, as the one in use at the Bureau of Chemistry of 
the United States Department of Agriculture (<?), but for a small room 
and with a comparatively small investment the present arrangement is 
all that could be desired. 
Records of the temperature and the humidity for one week are shown 
in Plate 48, B. The temperature can easily be regulated at 70° F., with a 
maximum variation of about 1 degree. The variation in the percentage 
relative humidity may be regulated to within 2 per cent on the bench 
where the samples are stored and measured, provided the desired per¬ 
centage is not over 70. Above this point there is a somewhat larger varia¬ 
tion when the door of the humidity room is first opened. 
SUMMARY 
(1) The breaking-strength determination as a measure of the strength 
of wool is unsatisfactory because of the wide variations in the size of the 
individual fibers. 
(2) The microscope was found an ineffective means of making a cor¬ 
rection for the diameter of the fibers. A micrometer substituted in place 
of the lower jaw of the testing machine proved to be very efficient in 
making this correction and reducing the breaking strength to tensile 
strength or unit stress. 
(3) Comparisons of the tensile strengths at five relative humidities— 
namely, 40, 50, 60, 70, and 80 per cent—showed that the tensile strength 
of raw wool from four different breeds of sheep decreases as the humidity 
increases. 
(4) Controlled conditions of temperature and humidity were obtained 
by means of electrical connections through a thermograph and a hydro¬ 
graph, operating, respectively, a bank of lamps and two atomizers. 
LITERATURE CITED 
(1) Barker, A. F., Barbrich, F. W., and Pickles, F. 
1912. THE EFFECT OR MOISTURE ON THE STRENGTH AND ELONGATION OR YARNS 
AND FABRICS. In Textile World Rec., v. 42, no. 5, p. 516-518; no. 6, 
p. 608-612; v. 43, no. 1, p. 127-130, 12 fig. 
(2) Hartshorne, W. D. 
1905. SOME COMPARATIVE DATA ON MOISTURE IN COTTON AND WORSTED. In 
Trans. New England Cotton Mfg. Assoc., no. 79, p. 194-225, ji fig. Dis¬ 
cussion, p. 220-225. 
( 3 ) -- 
1911. the laws op regain in cotton and worsted. In Trans. Nat. Assoc. 
Cotton Mfg., no. 90, p. 281-319, 5 fig. Discussion, p. 312-319. 
