INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 879 



under the excellent theoretical guidance of Professor Abbe, is due the 

 credit of being the first to take into account this new tendency. 



A year ago, the firm of Schmidt and Haensch following in the 

 footsteps of Zeiss, made improvements in the Microscope, and in 

 particular brought out their new movable stage. 



The first and oldest movable stage on Schmidt and Haensch's 

 model was placed on the ordinary stage, and very much distinguished 

 itself over those of English construction [i. e. the stage on j5. 713 !] in 

 being more simple, and entailing, therefore, a higher degree of 

 certainty and exactness * in the work. The motion from back to front 

 was produced by a screw, whilst the lateral motion (from right to 

 left) was effected by a simple lever-movement. This construction 

 did. not provide, it is true, for the diagonal motion of the object, 

 which is possible with English Microscopes, but, on the other hand, it 

 afforded what . is entirely wanting in English stages, an absolute 

 guarantee that no portion however small of the preparation can escape 

 the attention of the observer. The eminent im2)ortance of this in many 

 scientific investigations need not be insisted upon by us. 



One defect, however, of this stage of Schmidt and Haensch could 

 not be disguised, and that was that it appeared only suitable for 

 use with low powers. All other objections which have been brought 

 against it, especially those of Professor Johne of Dresden,t must bo 

 met with the rejoinder that they are either empty phrases or, as the 

 writer will prove in another place, erroneous conclusions drawn from 

 wrong calculations and false premises. 



Messrs. Schmidt and Haensch's manufactory has now produced 

 at the instigation of the writer and by the application of an idea of 

 Professor H. Goltzsch, two new movable stages, which are free from 

 the reproach we have admitted above, and which ought to satisfy all 

 requirements. 



There is the most absolute certainty, even when the highest 

 powers are used, that not even the minutest part of the preparation 

 will bo passed over ; whilst at the same time, like the Maltwood 

 finder, it serves to find again readily any particular point of tho 

 preparation. 



An essential advantage of tho new stages over English ones 

 consists in the fact tliat, besides the simplicity and certainty of their 

 construction, the larger one can also be used as a screw micrometer, 

 and both allow of a much greater use being made of the optical capacity 

 of the Microscope, on account of tlieir being considerably thinner than 

 the English movable stages, whereby a better adjustment of the 

 diaphragms (c. g. raising the diajihragms to the under surface of the 

 slide without using tho condensers) is rendered possible. 



Tho two stages are designed on a ccmimon principle, but difier 

 from each other by one being intended for rapid work with low and 

 medium powers (uj) to GOO), whilst the other is for exact scientific 

 investigations and measurements, in which the highest powers may bo 

 used. 



* AM ifnlifH ns in original toxt. t ^''O tliis Jonrnal, ante, p. 71.S, 



