142 Yoigtlaender & Sohn, Braunschweig. 



In the earlier part of the period to which we have alluded, viz 

 in the years 1840 to 1860, photography spread very slowly; its methods 

 were intelligible to only a small number of the scientifically educated; 

 moreover the photographic lens of that time still possessed a serious 

 fault, the difference of the chemical and optical foci, which, though 

 apparently an easily curable defect in its practical consequences yet 

 greatly retarded the popularity of photography. 



In 1856 the firm succeeded in eliminating this defect by introducing 

 another glass so as to form a compensating element. Shortly after the 

 Collodium process became Known, and it may be said that at this time 

 portrait photography began seriously. Also the Orthoscope, the first 

 landscape lens, which possessed a larger field, became only then practi- 

 cally useful; though its construction had been in the possession of the 

 firm as early as 1841. 



A few years after the publication of the first photographic lens 

 an improvement was also made in the construction of the binoculars 

 by the introduction of triple objectives and triple eye-pieces, whereby better 

 means w r ere obtained for the compensation of spherical and chromatic 

 aberrations and also for the increase and aplanation of the field. These 

 binoculars with 12 glasses became, particularly in England, very popular, 

 more especially so when the firm some 30 years ago took up the manu- 

 facture of the mounting of the binoculars in brass and aluminium. The 

 variety of these binoculars is very large indeed. Binoculars are made 

 magnifying only 2V 2 to 4 times for the theatre, and of higher power, 

 magnifying up to 8 times, for out-door use. These are mounted in a great 

 variety of forms, as the catalogues shc^jv (No. 1 to 56). 



In the course of years, however, the firm had to yield to the variety 

 of the demand, in particular to that of the German Navy, for optically 

 more simple marine glasses with double objectives and single eye-pieces, 

 containing, therefore, only 6 lenses. Accordingly such simplified binoculars 

 with a large and bright field are now made and supplied to nearly all 

 fleets of the world, in particular to the German Navy, the U. S. Navy 

 and a special form with rapid movement to the Artillery of the German 

 Army. Among the exhibits will be found a sample of this latter binocular, 

 5000 of which have recently been ordered by the German Army-admini- 

 stration, and also the aluminium model which has been adopted by the 

 War Department in Washington. 



While these binoculars were being improved and introduced to the 

 public, attention was also paid to the improvement in the construction 

 of hand-telescopes with terrestrial eye-pieces. These also are made by the 

 firm in various sizes, with object glasses from 1 inch to 2V 4 inch diameter, 

 magnifying 14 to 36 times, fitted either with one drawer of the form 

 adopted by the German navy, made of nickeled German silver, or with 

 three draw-tubes of brass and aluminium for sporting and military purposes. 



As long as the collodium process held the monopole, photography 

 remained almost exclusively in the hands of professional photographers. 

 The invention of dry plates opened the field to the amateur about 15 years 

 ago. These greatly simplified out-door photography; landscape and archi- 



