12 



SECTION 2. GEOMETRY. 



WEST GALLERY, GROUND FLOOR, ROOM G. 



I. INSTRUMENTS USED IN GEOMETRICAL 

 DRAWING. 



52. Pantograph. 



Royal School of Industry, Cassel. (Dr. W. Narten.) 



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

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

 and diminishing maps and plans. Peculiar to this construction is the move- 

 ment of all the arms in 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, as by this means all 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 Son, and the instrument possesses in consequence 

 great accuracy and facility of use. 



53. Pantograph. Renaud Tachet, Paris. 



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



Albert Ott and Gottlieb Cwadi, Kempten. 



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

 be transferred either on 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 elastic metal wires from cast-iron crane-like frames ; thus only a small 

 portion of each; 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 graphically reproduced. Drawings, like- 

 wise, can be transferred on substances measuring a certain height, such as 

 lithographic stones, it being only necessary to place frame and original corre- 

 spondingly higher. In producing enlarged copies both 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 y 1 ^. 



L. Oertling. 



