Sept. 8 , 1923 Determination of Surface Area of Cattle and Swine 423 
Obviously, the posture of the animal has little or no effect on the meas¬ 
urement we have chosen. Furthermore, we do not believe that the 
uncertainty as to the location of the point of withers will cause any real 
difficulty. The measurements from which our formula was derived were 
taken by several observers, and so represent the probable range of varia¬ 
tion in the selection of those points. Our calculated results would hardly 
agree so closely with the measured area if these variations are of great 
moment. In order to indicate more clearly the location of these points 
they have been shown on Plate 1. 
In anatomical terms the “ point of the withers/' as we have determined 
it, seems to lie directly above the juncture of the second and third tho¬ 
racic vertebrae. The end of the ischium is the tuber ischii, commonly 
called the pin bone. The point of the withers of swine, as we have 
taken it, lies above the juncture of the first and second thoracic vertebrae. 
The root of the tail is, of course, the point where tail and body join. 
WEIGHT 
Besides the “ length of body," also the weights of the animals were 
used in developing the formula. This is simply the weight of the animal 
taken at the time the surface area was measured. Neither food nor 
water was withheld from the animals before weighing. 
DESCRIPTION OF ANIMAI^S 
The cattle were in practically all cases of beef breeding variety and 
varied from scrubs to the purebred. They varied in age from about 
6 weeks to 8 years, and in condition from very thin to very fat. The 
weights range from 55 to 842 kgm., and the length of body ranges from 
61 to 172 cm. The data include four females, two heifers, and two dry 
cow^ 
The swine were purebreds, including Poland China, Duroc Jersey, and 
Yorkshire breeds. They varied in age from 3 weeks to over 3 years, 
and in condition from very thin to very fat. The live weights ranged 
from 2.5 to 178.1 kgm., and the length of body ranged from 24 to 132 
cm. Both barrows and females were included. The data used in ^devel¬ 
oping the formula for cattle are given in Table II and for swine in 
Table III. 
