TRANSACTIONS OF SECTION G. " 673 



engines and other sources of exhaust steam. Several such installations are 

 described and the high economy attained by such turbines is explained. 



As a steam turbine can utilise the highest vacuum attainable to its full extent, 

 the use of the vacuum augmentor described in a paper before the Institution of 

 Civil Engineers read in December 1905 is given, with some instances of the hio-h 

 vacua obtained in practice by its help. 



In conclusion the marine turbine was briefly touched on, and the great 

 development from the little ' Turbinia ' of 1897 to the gigantic Cunard express 

 liners of to-day was described. 



• 3. An Application oj Stream Line Apparatus to the Determination of the 

 Directions aiid Approximate Magnitudes of the Principal Stresses in 

 certain portions of the Structure o_f Ships} By J. Smith. 



4. On the Teaching of Mechanics."^ By C. E. Ashford, M.A. 



Brief description of the conditions governing the teaching of mechanics in the 

 new scheme of naval training, consequent on cadets receiving an engineering 

 training in workshops and lecture-rooms concurrently with a scientific and general 

 education in laboratories and class-rooms during four years from the age of 

 thirteen. 



The result of this close co-operation of the schoolmaster with the engineer is 

 to prevent the teaching of mechanics from becoming academic on the one hand, or 

 rule of thumb on the other. 



School science is seriously in danger of becoming as academic as classics, 

 largely from the influence of the Universities, which train the masters, and from 

 the preponderance originally given to chemistry. So far as mechanics was taught, 

 it was taken originally by the mathematicians as a pure effort of the imagination 

 and mathematical reasoning powers. Even now the physics master, where he 

 exists, has not sufficiently broken away from these lines. Mechanics is quite 

 rightly used to gild the pill of mathematics and to give reality to that subject ; 

 but no one in a school is able by his training to provide the necessary counter- 

 poise of actuality. Science masters have been trained on toys and models, and on 

 taking up teaching find their laboratories fitted with them; if they have to 

 arrange courses of mechanics, they are accustomed to deal with scientific instru- 

 ment makers (who supply only models often more costly than the real thing). Often 

 they do not know where to obtain actual machines, like screw-jacks and Weston's 

 blocks, which are better for both lecture-room and laboratory. The technical 

 school avoids this fault, but often lacks the good influence of the rigorous mathe- 

 matician and the trained educationist. 



The ideal system seems to be to combine under one roof the skilled engineer, 

 the science master, and the schoolmaster experienced in giving a wide general 

 and literary education, and to carry on their teaching simultaneously for a period 

 long enough to allow each to give what he considers essential. 



Another difficulty in the school teaching of mechanics is the present lack of 

 experimental apparatus for showing the phenomena of kinetics. This has been 

 met by Mr. W. C. Fletcher's recent adaptation of the trolley to this purpose, 

 together with the work since done by many teachers. Some examples in this 

 direction, as well as other pieces of apparatus, which have been designed by the 

 staff of the Royal Naval College, Dartmouth, may be of interest. Among others 

 the following will be described and illustrated : — 



Trolleys adapted to illustrate Newton's Second Law of Motion, the conserva- 

 tion of linear momentum (including recoil of a gun), to demonstrate the transfor- 

 mation of potential into kinetic energy, to investigate the laws of rotation about 



' Published in Engineeri'ng, September 28, 1906. 

 ' Published in School World, September 1906, 



1906. X X 



