862 EXPEEIMENT STATION RECORD. 



valve which permitted the subject to inhale and exhale by the mouth, the nose 

 being closed. The work done in performing each task and the corresponding 

 expenditure of energy by the body were measured by an especially designed 

 ergograph. The curves obtained in this way were calibrated in kilograms and 

 showed the various components of the forces applied by the body. At the same 

 time the heart beat, pulse rate, and blood pressure were determined. Respira- 

 tory curves were obtained under conditions of normal fatigue and overfatigue, 

 which, together with the arterial pressure, made it possible to follow the course 

 of the functions essential to life during the performance of the task and to 

 avoid excessive efforts on the part of the worker which might injure the 

 organism. 



In applying the results of these experiments to practical work in filing metal, 

 the effect upon the respiratory exchange of varying the pressure, the con- 

 traction, the rhythm and length of the movements of the file, the position of the 

 worker, and the intervals of rest were studied. The work of an experienced 

 workman was also compared with that of an apprentice. Employing this same 

 means, the laws which determine the most economical expenditui'e of energy in 

 the performance of several tasks were also studied. 



The fundamental factors studied in the case of the various tasks investigated 

 were the amount of the contraction of muscle, the time during which it was 

 sustained, the speed of the body movements, and the relation of the work 

 periods to rest periods. The following conclusions are drawn from these studies : 



The expenditure of energy is proportional to the length of the effort and 

 degree of muscular contraction. 



The expenditure of energy to produce a given task diminishes in proportion to 

 the speed of contractions. This is true only within certain limits which produce 

 serious physiological disturbances, such as alteration of muscular and nervous 

 tissues when exceeded. 



There is an optimum speed at which the maximum work may be obtained 

 with the least fatigue, and this should be the true object of scientific manage- 

 ment of industrial labor. 



The rapidity of recovery of the muscle during rest is proportional to the rate 

 at which it works. The oxygen consumption which indicates this rate may thus 

 indicate the need of rest periods. 



The price of labor expressed in terms of food fuel {Jour. Amer. Med. Assoc, 

 62 ilBlIt), No. 24, pp. 1895-1897).— This article deals briefly with the question of 

 the relation of the kind of work performed to the daily requirement of energy in 

 the food. 



ANIMAL PRODUCTION. 



Digestion experiments with Texas feeding stuffs, G. S. Fraps (Texas 8ta. 

 Bui. 166 {1914), PP- 5-26). — This bulletin reiwrts the results of digestion trials 

 made with six sheep on various feeding stuffs. The experiments with the 

 concentrates were carried' out in several periods of 12 days each. In the first 

 and last periods, alfalfa hay was fed, and in the other periods the concentrates 

 to be tested were added, using 300 gm. of hay to 300 gm. of concentrates per 

 day. The ration to be tested was fed 12 days, and the excrement collected 

 during the last 6 days. 



The average coefficients of digestibility of feeding stuffs, as reported by vari- 

 ous experiment stations and including those found in these trials, together with 

 the productive values of these feeds (pounds of fat produced by 100 lbs. of the 

 feed, when fed in addition to a maintenance ration) are given in tlie table 

 following. 



