Introduction. 7 



particular the instruments constructed for the examination of sugar and wine, 

 which are as simple in construction as they are perfect in workmanship. The 

 competention between gas and electric light has, as in other countries so also 

 in Germany, occasioned important improvements in the province of photometric 

 apparatus. In this direction the influence of the Physical and Technical Institute 

 has been most marked, two of its members, Mssrs. Lummer and Brodhun, 

 having devised an ingenious combination of prisms which eliminate an 1 innate 

 defect of Bunsen's photometer and formed the basis of technically valuable 

 appliances. 



The local distribution of optical manufacture in Germany is as follows: 



1) Astronomical telescopes: Munic, Berlin; 



2) Photographic objectives,: Munic, Jena, Brunswick, Berlin, Rathenow ; 



3) Microscopes: Jena, Berlin, Wetzlar, Potsdam, Gottingen; 



4) Binoculars and other terrestrial telescopes: Munic, Brunswick, 

 Berlin, Rathenow; 



5) Spectroscopic Apparatus, Polarimeters , Photometers: Berlin, 

 .Munic, Hamburg, Jena; 



6) Mineralogical preparations (Quartz andcalcite): Homburg, Berlin. 

 Not less important are the Measuring instruments for special purposes 



in physical science made by German makers with that degree of precision 

 which modern physical research demands. We cannot here enter into detailed 

 enumeration of the numerous instruments of this class but will only remind our 

 readers of the crystallographic instruments for determining the geometrical and 

 physical constants of crystals. -- The manufacture of Chemical apparatus is 

 greatly supported by the highly developed glass-industry of Germany, which is 

 centralized in the Thuringian districts. 



The glass industry of Thuringia embraces the manufacture of glass-house 

 and blow-pipe goods. Both these divisions envolve a series of incidental operations, 

 such as glass-grinding, polishing, etching, sandblasting, graduating, standardizing 

 and so forth. 



The glass-house goods comprise mainly: 



1) Glass-tubing for glass -instruments (thermometers, hydrometers, 

 barometers etc.). Glass-houses for these goods are in Gehlberg, 

 Stuetzerbach, Geyersthal, Frauenwald and Jena. The Jena glass- 

 house supplies the Jena standard thermometer glass, which is so 

 distinguished for its minimal thermal defects; it also makes glasses 

 for high temperature thermometers and compound glass tubes; 



2) Glass tubing for the manufacture of artificial fruits, flowers, pearls, 

 toys etc. Glass-houses for these goods are e. g. in Schmalenbuche 

 and in Ernsthausen; 



3) Hollow-glassware and glass-apparatus for chemical, physical, pharma- 

 ceutical, surgical and clinical, commercial and other purposes. This 

 division includes in particular: Boiling flasks, beakers, funnels, cy- 

 linders, air-pumps, incandescent lamps etc. The center 'of manu- 

 facture of these goods is Stuetzerbach ; but they are also made in many 

 other places, e. g. Gehlberg, Ilmenau, Graefenroda and Geyersthal. 



