SECTION 2. GEOMETRY. 







WEST GALLERY, GROUND FLOOR, ROOM G. 



. i& 



L INSTRUMENTS USED IN GEOMETRICAL 

 DRAWING. 



52. Pantograph, by Breithaupt and Son. 



Royal High School of Industry, Cassel. (JV. Narten.) 



This pantograph was made for the geodetic collection of the school, in the 

 year 1866, by Messrs. Breithaupt nnd Son, Cassel. It is used for enlarging 

 and reducing maps and plans. The peculiarity of its construction is the 

 movement of all the arms between pairs of points, by which means friction 

 is as far as possible avoided. The employment of tubes instead of the usual 

 rectangular bars is also to be recommended, by which means bending, which 

 creates errors in the use of the instrument, is avoided ; besides which, the 

 weight of the whole is considerably decreased, thus also lessening friction in 

 the movement of the points. 



The peculiar construction of this pantograph was invented and carried out 

 by Messrs. Breithaupt and Sou, and the instrument possesses great accu- 

 racy and facility of use. 



53. Pantograph. Menaud Tachet, Paris. 



54. Pantograph, with free hanging arms of new construction. 



Ott and Coradi Kempten, Baviera. 



By means of this instrument figures on a reduced or an enlarged scale can 

 be transferred either to paper, stone, or metal. 



These pantographs differ in their construction from other similar instru- 

 ments by not resting on friction-rollers, but are freely suspended by means 

 of metal wires from cast-iron curved standards ; thus only a small portion of 

 the weight of the instrument rests on the table. The advantages of this con- 

 struction are these : easy and secure management of the instrument ; any 

 ordinary table may be used of a size sufficient to afford room for the stands, 

 the original, and copy ; the accuracy of the graphic representation is greater 

 at less cost. 



The guidance of the instrument is so easy and so accurate that with a 

 little practice every outline can be reproduced. Drawings, likewise, can be 

 transferred to substances measuring a certain height, such as lithographic 

 stones, it being only necessary to place frame and original correspondingly 

 higher. In producing enlarged copies the guiding peg and the drawing pencil 

 must be exchanged, and the releasing cord fastened accordingly. The guidance, 

 in making enlarged copies, is also performed with the handle of the tracing 

 pencil with the same accuracy as when making reduced copies. 



54a. Horizontal Pantograph, traversing a surface of 36 

 inches in length by 20 inches in width. Reduction from \ to T ^. 



L. Oertlina. 





