TRANSACTIONS OF SECTION G. 877 



' intellectual activity excited by the work which the civil engineers of England had 

 ' accomplished that gave to philosophy the theory of the conservation of energy 

 4 including the dynamical theory of heat. . . . The engineering genius of the future 

 ' is certain to derive from this theory strength and guidance. Thus necessarily has 

 ' thought originated fact, and fact originated thought. In the development of 

 ' science these two powers are coequal ; each in turn ceasing to he a consequence, 

 ' and becoming a creative cause. The Atlantic cable also had its small beginnings 

 ' in the laboratory of the physical inquirer. Here, as before, experimental physics 

 Med the way to engineering facts of astounding magnitude and skill. But here also 

 ' the positions of debtor and creditor have been reversed, for the work of the 

 ' engineer has caused the physical inquirer to pursue his investigations with a 

 ' thoroughness and vigour, and has given to those investigations a scope and magni- 

 ' tude which, without the practical stimulus, would have been impossible. The 

 ' consequence is that the practical realisation of sending electric messages along the 

 ' bottom of the Atlantic has been an immense augmentation of our knowledge 

 ' regarding electricity itself. Thus does the human intelligence oscillate between 

 ' sound theory and sound practice, gaining by every contact with each an accession 

 ' of strength. These two things are the soul and body of science. Sever sound 

 ' theory from sound practice, and both die of atrophy. The one becomes a ghost 

 ' and the other becomes a corpse.' 



I think all men, even although they be followers of science in its purest and 

 most abstract form, must agree that these words are words of sound sense, well 

 worthy of being borne in mind and of being acted on, and will, therefore, concur 

 in the propriety of Section G dealing with engineering subjects generally as well 

 as with abstract mechanical science. Once admitting this, I may ask — certain what 

 the answer must be — whether there is any body of men who more appreciate and 

 make greater use of the applications of pure science than do the members of this 

 Section. Surely every one must agree that we engineers are those who make the 

 greatest practical use not only of the science of Mechanics but of the researches 

 and discoveries of the members of the other sections of this Association. 



Section A, Mathematical and Physical Science. The connection between this 

 Section and Section G is most intimate. With any ordinary man I should have 

 referred, in proof of this intimate connection, to the fact that the President of A 

 this year is a member of the Council of the Institution of Civil Engineers, but when 

 I remind you that it is Sir William Thomson who fills this double office, you will 

 see that no deduction such as I have hinted at can be drawn from his dual functions, 

 because the remarkable extent and versatility of his attainments qualify him for so' 

 many offices, that the mere fact of his holding some one double position is no certain 

 evidence of the intimate connection between the two. But setting aside this fact 

 of the occupancy of the chair of A by a civil engineer, let us remember that the 

 accomplished engineer of the present day must be one well grounded in thermal 

 science, in electrical science, and for some branches of the profession in the science* 

 relating to the production of light, in optical science and. in acoustics ; while, in 

 other branches, meteorological science, photometrical science, and tidal laws are all 

 important. Without a knowledge of thermal laws, the engineer engaged in the 

 construction of heat motors, whether they be the steam engine, the gas engine, 01- 

 the hot-air engine, or engines depending upon the expansion and contraction under 

 changes of temperature of fluids or of solids, will find himself groping in the dark; 

 he will not even understand the value of his own experiments, and therefore will 

 be unable to deduce laws from them ; and if he make any progress at all, it will 

 not guide him with certainty to further development, and it may be that he will 

 waste time and money in the endeavour to obtain results which a knowledge of 

 thermal science would have shown him were impossible. Furnished, however, 

 with this knowledge, the engineer starting with the mechanical equivalent of heat, 

 knowing the utmost that is to be attained, and starting with the knowledge of 

 the calorific effect of different fuels, is enabled to compare the results that he 

 obtains with the maximum, and to ascertain how far the one falls short of the 

 other; he sees even at the present day that the difference is deplorably large, 

 but he further sees hi the case of the steam engine, that which the pure scientist 



