20 Piof. llcluilioltz on the Telestereoscope. 



landscape, the dimensions of whicli arc to tbose of the landscape 

 as the distance between the two eyes is to the distance between 

 the two positions of the camera from which the views were 

 taken. 



We have here the reason why these stereoscopic images give 

 a much clearer representation of the form of a landscape than 

 the view of the landscape itself, at least to a passing traveller, 

 who is not so well acquainted as the inhabitants with the single 

 objects of the neighbourhood. Towns, which to the observer on 

 a high point, a])pear merely as a desert of roofs, resolve them- 

 selves in the stereoscope to rectangles bounded by streets ; the 

 relative height of the houses is discerned, the width of the streets, 

 &c. In accordance with this, I find that a better idea is obtained 

 of the gigantic dimensions of the higher Alps in the stereoscope, 

 than by an alpine journey; because those who are unaccus- 

 tomed to such mountain excursions and prospects in most cases 

 consider the mountains too near, and hence too small, partly 

 from the want of aerial perspective, partly because the power of 

 judging of such great dimensions has not been exercised. Only 

 after the labour of ascent, and after viewing the same mountain 

 successively from different positions, is a more or less complete 

 notion of its magnitude obtained. The advantages which the 

 stereoscope offers in this respect have been thus far but little 

 used, because photographers on the whole seem unjustly to 

 avoid making use of a great distance between the points whence 

 the views are taken. It may be perceived that, for example, 

 bodily images of the most remote parts of the higher Alps may 

 be obtained when points are chosen for the taking of photo- 

 graphic views some thousands of feet distant from each other. 

 AVhile inspecting good models of these mountains, I have always 

 found that I had obtained very incomplete notions of the moun- 

 tain groups from a journey through the country. In general I 

 had squeezed them too closely together, and represented their 

 bases too small. Here doubtless also is to be found the reason 

 why models of mountains with exaggerated heights please us 

 better than such as represent the elevations on a correct scale. 

 "The formei' correspond more to the impressions which we receive 

 on a hasty journey through a mountain country. By means of 

 a little instrument which I have named the telestereoscope, a 

 portion of the advantage possessed by stereoscopic photographs 

 may also be realized while looking directly at a landscape. The 

 olijectof the instrument is to present stereoscopically united two 

 pictures of the landscape corresponding to two points of view 

 whose distances cotisiderably exceed the distance between the 

 two eyes. The annexed figure shows a mean horizontal section 

 of the iustrumcjit, onc-clcvcnth of its natural size. 



