vi PREFACE 



express each by a simple formula. Finality is not claimed. 

 On the contrary it may be hoped that the obvious defects of 

 the formulae, which are also inherent, though not so apparent 

 in the feeding standards, will be made the subject of special 

 research. It may be claimed, however, that the formulae are 

 of more general application than the feeding standards, and 

 that they yield a closer approximation to the truth regarding 

 the requirements of the animals in any given case. 



The work is essentially quantitative in character, and in 

 order to master the principles it is necessary to grasp the 

 reasons for each step in the calculations. The interest of 

 novelty attaches to the graphic solutions of problems in 

 compounding rations described in Chapter XIV., and they are, 

 perhaps, not without educational value. One of them at least 

 has the merit of simplicity, and, in conjunction with the 

 natural classification of the feeding stuffs according to their 

 position on the chart, may prove to be of practical utility. 



The book is intended mainly for the use of students 

 pursuing college courses in agriculture, but it is hoped that it 

 may be useful also to practical farmers who have some previous 

 knowledge of chemistry. For this reason English standards of 

 mass and measurement are adhered to throughout; but in 

 order to simplify the calculations and facilitate comparison 

 with the metric system only decimal multiples of the funda- 

 mental units are employed. The adoption of the " kilo-pound 

 unit," i.e. the amount of heat required to raise the temperature 

 of 1000 Ibs. of water i C., is no doubt open to criticism 

 No justification, save that of convenience; is offered either for 

 the thing or for the name. 



The author gratefully acknowledges his obligation to all 

 the great army of predecessors and fellow workers as well as 

 to the authorities more particularly mentioned in the text. 

 Thanks are due also to Mr. J. W. Dodgson and others for 

 criticism and suggestions and for assistance in revising proofs. 



READING, 

 Nov., 1913. 



