34 Transactions of the Society. 



by the projection no new errors are introduced, since the projection 

 system is corrected as well as the objective, and in particular is free 

 from secondary colour dispersion and the focal difference which results 

 from it. 



In addition, care is also taken that in the final image the chromatic 

 difference of magnifying power in the objective image is removed with 

 the projection system just as it is with the compensation eye-pieces. 



The whole manipulation for focal adjustment can be managed as 

 well for short as for long distances of the plate, and is in this method 

 particularly simple. 



Such systems for projection, which are in external form like eye- 

 pieces, and are attached to the Microscope in the same way, are designated 

 projection eye-pieces. 



The results already obtained by experienced photomicrographers by 

 the employment of this method make it probable that it will come into 

 general use in the future. 



