NOVEMBEB 18, 1921] 



SCIENCE 



479 



following sounds in answer: eff equals emm 

 aye! Do not tolerate the mere reading of an 

 equation in answer to a physical question. 



Do not tolerate vague statements. It is 

 physically meaningless to say, for example, that 



acceleration is gain of velocity divided by 

 time." The proper statement is that the aver- 

 age acceleration of a hody during a given time 

 is equal to the velocity gained hy the tody dur- 

 ing the given time divided by the time. It is 

 meaningless to say that " density is mass 

 divided by volume." The proper statement is 

 that the density of a body is equal to the mass 

 of the body divided by its volume. 



Require the student to make every statement 

 of definition, every statement of principle, every 

 explanation of an equation, etc., as relating ex- 

 plicitly to a particular condition or thing. 



The natural desire for brevity of statement 

 is often allowed to go much farther than the 

 elimination of the important element of ex- 

 plicitness as above pointed out, and lead to 

 complete obscurity of meaning as illustrated by 

 the following example : A string 10 feet long is 

 tied to a post and a force of 5 " pounds " is ex- 

 erted on the post by pulling the string. This 

 force certainly " acts through a distance of 10 

 feet," and, the work done is 50 foot-" pounds " 

 because " work is done when a force acts 

 through a distance." This argument is found 

 to be acceptable to about 60 per cent, of the 

 men beginning a college course in mechanics I 

 No! Worle is done when a hody on which a 

 force acts moves in the direction of the force, 

 and no dictionary ever defined the word through 

 in a way to justify the use of the word to abbre- 

 viate this 18-word statement as it is usually 

 abbreviated in the study of physics (?) in 

 school and college. Language has been devel- 

 oped as a medium for dickering, quarreling and 

 love-making, and language as used in precise 

 physical specifications is always more or less 

 awkward and more or less strained ; but it is a 

 serious mistake to obviate these things by 

 using meaningless expressions and phrases. 



I have never talked with an electrical engi- 

 neer who retained any helpful knowledge or 

 understanding whatever from the study of elec- 

 trostatics in his college course in physics; and 



every electrical engineering teacher will tell 

 you that he cannot count on any knowledge or 

 understanding, even incipient knowledge and 

 understanding, of electrostatics among stu- 

 dents who have just finished their college 

 course in physics. Wm. S. Franklin 



Massachusetts Institute or Technology 



REQUIREMENTS OF A MONOGRAPH 

 ON THE CHEMISTRY OF CELLULOSE i 



In a seminar devoted exclusively to the 

 chemistry of cellulose certain topical assign- 

 ments were made to the students, who, after a 

 careful and critical survey of the literature, re- 

 ported their findings. The course served to 

 emphasize a number of sad facts that are un- 

 doubtedly known to all students in the field 

 of cellulose chemistry. We were impressed by 

 the enormous number of undigested, uncorre- 

 lated facts that had been amassed apparently 

 as a result of teclmological studies. We were 

 further impressed by the relatively small num- 

 ber of fundamental studies (bearing the ear- 

 marks of painstaking critique on the part of 

 the investigator) that had a direct bearing on 

 the constitution of cellulose, and by the amaz- 

 ing method of presenting these facts in our 

 best English text. It became quite evident as 

 our course proceeded, that there was a lack of 

 vision in the interpretation of noteworthy re- 

 sults in the literature ; that little attention had 

 been paid to the methods employed or judgment 

 exercised by investigators in the experimental 

 portions of their work ; that scant attention had 

 been given to the correlation of isolated experi- 

 mental data, and that little differentiation had 

 been made between qualitative and quantitative 

 data in the formulation of hypotheses. To pre- 

 sent the case briefly — it became very apparent 

 that a critical monograph in the English lan- 

 guage was little less than a necessity. Since 

 the close of our seminar, Heuser's new " Lehr- 

 buch der Cellulose Chemie " has appeared, and 

 this splendid work will receive further men- 

 tion. 



A few examples will serve to illustrate the 

 various points previously raised. Take the 

 1 Read at the meeting of the AmerieaJi Chemieal 

 Society, New York, September 9. 



