838 



SCIENCE. 



[N. S, Vol. VII. No. 181.. 



or scissors." A foreign critic's comment upon 

 this was : " Sad, indeed, if true ! " 



Most teachers of science who have labora- 

 tories to control, whether in chemistry, physics 

 or biology, will probably be ready to express 

 their accordance with the view of the chemical 

 writer. No one can direct students in a phys- 

 ical laboratory without fiuding that his own 

 needs are not met in any one of the consider- 

 able number of laboratory guide books with 

 which the market now abounds. Nor would he 

 be any more fortunate if the number of these 

 became tenfold greater. No two laboratories 

 are alike ; no two teachers are alike. Every 

 laboratory manual is a compound product of 

 teacher, laboratory and special circumstances. 

 It is never made deliberately for the purpose of 

 instructing the world at large, but specially 

 for one laboratory in particular. It is then 

 published, in the hope that its contents may be 

 useful in other laboratories. 



The earliest laboratory manual for students 

 in physics, that of Kohlrausch, was written so 

 concisely that, while apparently as good for one 

 laboratory as for another, it was found by its 

 users to be always in need of supplementary 

 matter. Each instructor usually prepares 

 special cards with such directions as are found 

 needful under given conditions of use. The 

 instructor must in any case be within reach to 

 respond to the student's needs ; but there is 

 great saving of time, breath and patience if 

 everything is plainly written or printed that 

 can be reasonably demanded by a student of 

 ordinary ability. Laboratory work is far su- 

 perior to class work in revealing the possession 

 or absence of that power of quick discernment 

 and practicality which is colloquially called 

 'gumption.' The student who is naturally 

 blessed with this power needs but little more 

 than the instruction cards, but there are al- 

 ways some who cannot be kept from blunder- 

 ing even if the instructor is continually present. 

 These are the ones that sap his energies ; and in 

 self-defense he is often compelled to adapt his 

 cards to them, giving specific directions ad- 

 justed to the particular apparatus to be em- 

 ployed, anticipating the mistakes they will 

 make, and sacrificing educative aims to the 

 need of saving apparatus from injury. 



Since the primary function of a laboratory 

 manual is thus to save time and labor for both, 

 instructor and student, it follows almost as a 

 necessity that each laboratory must be provided, 

 with its own manual. If this be printed, con- 

 venience is temporarily promoted. But eachi 

 year brings changes. Old cards must be modi- 

 fied or new ones written, or the laboratory 

 manual must be subjected to frequent revision. 

 Manuals prepared for other laboratories must, 

 it is true, be at hand for ready reference. They 

 are highly useful, but never suflicient, because- 

 not adapted to the particular apparatus which 

 the student is called upon to master. 



The small volume of a hundred pages by 

 Messrs. Stratton and Millikan is an excellent 

 index of the good work through which junior- 

 students are carried in the Ryerson laboratory, 

 of the University of Chicago. It bears much 

 internal evidence that its authors were writing 

 specifically for their own students, and writing- 

 with a degree of intelligence that indicates how 

 successful their work must be. The book opens 

 with some general directions regarding the 

 method of making observations, keeping records 

 of these, and estimating the accuracy attainable 

 under given conditions of work. The exercises- 

 are grouped under three heads. Mechanics, 

 Molecular Physics and Physics of the Ether. 

 Under the former are included various methods 

 of measuring distance, direct and indirect de- 

 terminations of the acceleration of gravity, an 

 excellent discussion of the use of the balance, the- 

 determination of density for solids and fluids, 

 elasticity of tension and torsion, composition- 

 and resolution offerees, the ballistic pendulum, 

 work and efiiciency. The instructions are for- 

 the most part given very clearly, and in each 

 case followed by a form of record with blanks- 

 to be filled in by the student. The last feature 

 may at first seem a little procrustean, but the 

 value of such specific guides is best appreciatedi 

 by those who have had most experience in the- 

 wearisome work 9f examining report books. 



Under the head of Molecular Physics are con- 

 sidered the surface tension of liquids, the prop- 

 erties of gases, hygrometry, thermometry,, co- 

 efficients of expansion, specific heat, energy of 

 fusion and vaporization, and methods- of de- 

 termining the velocity of sound. 



