22S On Practical Scientific Instruction. [April, 



several sciences, including physics and chemistry; and therefore the 

 employments connected with it, and the technical education relating 

 to it, also necessarily include a knowledge and an explanation of 

 the chief laws and principles of those sciences : for example, the 

 manufacture and working in metals requires a knowledge of the 

 sciences of mechanics, heat, and chemistry; the occupation of 

 electro-plating necessitates a knowledge of electricity and chemistry; 

 the numerous employments involving the construction or use of 

 tools and machinery require a knowledge of the science of me- 

 chanics, and in some cases also of heat and chemistry. 



The fundamental laws and principles of any particular science 

 operate in a similar manner in all trades, and are substantially the 

 same for all learners : for example, the same chemical and electric 

 principles operate in the galvanic batteries of telegraphists and 

 electro-platers, as in those of the scientific investigator ; the laws of 

 combustion are the same in a puddler's furnace as in a domestic fire- 

 place ; water boils at the same temperature, whether it be in a chemist's 

 flask, a brewer's copper, or in a servant's saucepan ; the laws and 

 principles of science, therefore, cannot be readily subdivided to suit 

 particular trades. With the practical illustrations, however, the 

 case is different ; they may be selected from particular occupations, 

 manufactures, arts, processes, and substances, so as to make the 

 ns suitable for different classes of persons, and thus ying 



the kind of illustrations the lessons may be adapted to persons of 

 different occupations, to agriculturists, metallurgists, and others. 

 In courses of lessons or lectures on technology, the teacher should 

 be very careful to select as many of the illustrations as possible 

 from the actual working experience involved in the particular trades 

 or occupations of his audience, and in this way the highest science 

 may be united to the meanest art. A difficulty connected with the 

 carrying out of this plan is. technical processes are rarely well under- 

 stood by professional teachers, because those processes depend so 

 much upon practical details. 



The technological teacher must know both the science of the 

 manufacture and the details of the manufacture itself to which 

 that science is applied ; he must be able to combine theory and prac- 

 tice, and continually to show the relation of abstract laws and prin- 

 ciples to technical results. He must not only know how difficult 

 things are done, but he must also to some extent be able to do them, 

 and thus to teach by example as well as by precept. His teaching- 

 must be full of practical applications and familiar illustrations. Such 

 teachers are as yet almost unknown, and Faraday, in his evidence 

 already referred to. stated that the class of men suitable for teaching 

 science remained to be created. 



This statement made by Faraday still remains true. Our Uni- 

 versities have not yet supplied many schools with teachers eminent 



