Polytechnic Association. 849 



March 1, 1872. 



Prof. S. D. Tillman, in the chair; Egbert Weir, Esq., Secretary. 



Cutting Ieregulab Forms. 



Dr. Yirgil W. Blanchard, of Bridport, Vermont, explained his 

 machine for cutting irregular forms automatically in wood, iron or 

 stone, and exhibited a sample of the work in stone. The principle is 

 essentially the same as that of the Blanchard lathe. The difficulty in 

 cutting in stone hitherto has been two-fold. First, to produce a pat- 

 tern that the tracing-bar will run upon rapidly; and, second, to pre- 

 serve the sharpness of the cutting point. This machine produces, from 

 the model, a pattern which is almost a plane surface, and then trans- 

 posing the tracing and the cutting points, from that pattern a perfect 

 facsimile of the model may be produced. He read the following 

 description of the machine, written by J. E. Emerson, the inventor of 

 the movable tooth-saw : 



For the past fifty years many attempts have been made to devise 

 mechanism to automatically produce the irregular forms found in 

 carving, sculpture, bronze, etc., but which have till now signally 

 failed. This lathe, or engine, to which any amount of motive power 

 may be applied that may be requisite that will automatically pro- 

 duce any of the irregular forms found in carving, sculpture, bronze 

 work and engraving— that will produce every line and feature with 

 mathematical precision and certainty — that will work equally well 

 upon wood, stone or metal, that is simple in construction and easy to 

 manipulate, has long been wanted to meet a great and growing demand 

 in the field of the fine arts. 



Every want seems to be fully realized in this invention to which 

 reference is made. The difficulties in the mechanical problem solved 

 lyy this invention are five-fold in character. 



First, to devise a pattern of such a character so near a plane that 

 an anti-friction ball will roll rapidly upon its surface, and yet have 

 sudk a pattern produce the irregular form desired. 



Second, to have the cutting point so sensitive to the motions of the 

 tracing ball upon the pattern as to produce with mathematical cer- 

 tainty and precision every line and feature found upon the surface of 

 the pattern, in the material wrought, and yet, in the presence of all 

 this delicacy and sensitiveness in action, to be able to apply any 

 desired amount of force or motive power to the cutting point. 



Third, to be able to transfer the design of the same pattern to any 

 [Inst.] 54 



