HISTORICAL 



71 



opportunity offered by the commercial improvement in the manu- 

 facture and design of small electric filament-lamps of high intensity. 

 In the years 1915 to 1919 Vogt published in German various 

 communications on his clinical slit-lamp findings, his work of 

 these preceding years at Basle culminating in the publication of 

 his Atlas (5) in German in 1921, von der Heydt's English 

 translation of which appeared soon after in America. At this 

 date the various countries that had been involved in the distraction 

 of the War were only just 

 beginning to turn their 

 attention to new and con- 

 structive work, and their 

 ophthalmologists began to 

 learn of to them an almost 

 new subject at a time when 

 it had alreadv attained con- 

 siderable development in the 

 hands of Vogt in Switzer- 

 land. Koeppe, of Halle, also 

 did much work on the sub- 

 ject (3). Vogt's " Atlas " con- 

 tained very little on the sub- 

 ject of technique and in the 

 two or three years succeeding 

 1920 independent workers 

 evolved for themselves the 

 subject of technique, and 



Fig. 42. — Simultaneous comparison of 

 views by retroillumination and direct 

 illumination for localisation in depth. 



published many observations of their own, further impetus being 

 given to the subject by a summer demonstration which was given 

 by Vogt, in Zurich, in 1923 and again 1924. By now the writers 

 on the subject in various countries were becoming numerous and 

 whilst many published observations which they not unnaturally 

 assumed to be original subsequent reference often enough showed 

 previous evidence of similar findings by Vogt in his publications 

 of 1915 to 1919. Vogt had in these years for ever laid the clinical 

 foundations of this work. Later, in other countries, the names of 

 different observers became, in their own country, associated with 



