2 Introduction. 



power of hindering German scientists of 30 years ago from obtaining their 

 nstruments from French or Englisch rather than German makers. 



The causes of this retrogression in so important a department of industry 

 were partly to be/ound in the unhappy political and commercial condition of 

 Germany, but still more so in the deficient correlation between theory and 

 practice. By a happy coincidence men began to recognize the fact that the 

 prosperity of the scientific instrument trade depended mainly upon the coope- 

 ration of scientific and practical men, just at a time when Germany began 

 to rise politically and commercially. German mechanical and optical industry 

 owes, indeed, its present prominent position, which it has attained within the 

 last 20 years, to the judicious manner in which both these coincident factors 

 were made use of. 



The entire development of German mechanical art during this time has 

 emanated from the full appreciation of the principle that the practical maker 

 must know the intentions of .scientific men which are to be realized by the instru- 

 ments and also the limits of the required exactness, and, vice versa, that the 

 investigator must not be an entire stranger to the manufacture of his instruments, 

 but must know their theory and with critical knowledge only demand that 

 degree of exactness which is necessary for his work or which is attainable. 

 This amalgamation of theory and practice forms the basis of the activity of the 

 Deutsche Gesellschaft fiir Mechanik und Optik", which has now existed 

 for 15 years and whose members, composed of practical and theoretical men 

 from all parts of the empire, combine their efforts and give graphic expression 

 to the results thus obtained in the official organ of the Association, the ,,Zeit- 

 schrift fiir Instrument enkunde" (Journal of philosophical instruments), a jour- 

 nal which comprises the entire subject of scientific technique. The object of 

 the association being to maintain the scientific interest of its members, to solve 

 important technical problems, such as the adoptation of uniform screws and 

 tube-threads in the construction of instruments, and also to watch over the 

 social and political interests of the industry which it represents, it, naturally, 

 had to look upon the technical education of the rising generation of mechani- 

 cians and opticians as one of its prominent duties. Much, indeed, has been 

 done in this direction in Germany within the last 20 years. At the instigation 

 of the Association the Berlin School for Artisans (Handwerkerschule) formed the 

 first evening class for mechanicians, in which apprentices received tuition in 

 drawing, natural philosophy and other subjects which are of practical utility 

 to instrument-makers. This example was followed by numerous other towns 

 and, at the present time, every young mechanician has in most of the larger 

 towns an opportunity to acquire theoretical knowledge in his trade, in many 

 cases under the tutorship of prominent mechanicians ; a few of the larger works 

 have even gone so far as to appoint and maintain at their own expense special 

 teachers for their apprentices. 



Means were also provided for more advanced studies. In Berlin a class 

 was founded for journeymen mechanists and more recently also for electrical 

 engineers in which journeymen in a course of six months had the opportu- 

 nity of advancing their theoretical knowledge so far as to become competent 

 of holding the posts of fore-men, adjusters and other preferred appointments. 



