630 SEC. 15. GEOGRAPHY. 



3095. Triangular Frism. 



Geodetic Institute of the Royal Polytechnic School at 

 Munich, Prof. Dr. von Bauernfeind. 



The Three-sided Angle Prism, invented by the exhibtor in 1851, serves 

 for the measurement and marking out of right angles, and depends upon the 

 deviation of light by refraction and total reflection. See Bauernfeind's 

 " Elemente der Vermessungskunde ," 5th edition, 1876, Stuttgart, F. G. Cotta, 

 Vol. I., pp. 37-39 and 164, 165. 



3096. Distance Measuring Frism. 



Geodetic Institute of the Royal Polytechnic School at 

 Munich, Prof. Dr. von -Bauertffeind. 



The Distance-measuring Prism, also invented by the exhibitor in 1851, 

 but not applied to measuring distances until afterwards, serves for marking 

 off isosceles triangles in which the equal sizes are definite multiples of the 

 base. It is used in the same way as the three-sided angle prism. See 

 Bauernfeind's " Elemente der Vermessungskunde," 5th edition, Vol. I., 

 pp. 39-40 and 167 (No. 4), and Vol. II., pp. 90, 91. 



3097. Pentagonal Frism. 



Geodetic Institute of the Royal Polytechnic School at 

 Munich, Prof. Dr. von Bauernfeind. 



The Five-sided Angle Prism, invented by the exhibitor in 1869, serves 

 not only for the measurement and marking off of right angles and half right 

 angles, but especially for the laying down in position of two inaccessible 

 points, or points which cannot be directly observed. It may replace the 

 prismatic cross No. 4. See Bauernfeind's " Elemente der Vermessungskunde," 

 5th edition, Vol. 1., pp. 44-46 and 166-168. 



3098. Frism Cross. 



Geodetic Institute of the Royal Polytechnic School at 

 Munich, Prof. Dr. von Bauernfeind. 



The Prism Cross was invented by the exhibitor in the year 1851, and 

 was then described in a separate memoir (" Das Prismenkreuz," published 

 by F. Palm). It is described with later improvements in Bauernfeind's 

 "Elemente der Vermessungskunde," 5th edition, Vol. I., pp. 168-175, espe- 

 cially 173-175. Its object is identical with that of the subsequently invented 

 five-sided angle prism (No. 3), which, as already stated, may be used instead 

 of it. 



3099. Intersecting Compasses (Arcograph). 



Geodetic Institute of the Royal Polytechnic School at 

 Munich, Prof. Dr. von Bauernfeind. 



The Arcograph serves to describe upon a given chord a circle which 

 embraces a given peripheral angle. The exhibitor, by this invention, has 

 supplied the wants of the practical geometrician in solving, graphically, and 

 without construction Pothenot's problem and all the problems which are 

 described in geodesy as " Kuckwartseinschneiden ". See Bauerufeind's 

 "Elemente der" Vermessungskunde," 5th edition, Vol. II., pp. 167-173. 



3O99a. Portable Compass. Colonel Deoen } Bobruisk. 



