C/l. -Y] PREPARATION OF MODELS 331 



paper over the carbon paper using thumb tacks to hold the blotting 

 paper and the duplicating sheets in position. 



One should take the precaution to number each drawing as it 

 is made then confusion in the later processes will be avoided. 



S 496. Cutting out the Sheets for the Model. " With the 

 blotting paper, if the drawings are small the cutting is easily done 

 with scissors or a knife. When the drawings are large and espec- 

 ially when the model is to be made by representing each section by 

 two or more thicknesses of blotting paper it has been found that an 

 ordinary sewing-machine can be used to do the cutting. By setting 

 the regulator for the shortest stitch an almost continuous cut is 

 made and the parts are easily separated. If a large sewing-machine 

 needle is sharpened in the form of a chisel, the cut becomes consid- 

 erably smoother. It has been found advantageous when long con- 

 tinued or heavy work is to be done to attach to the machine an 

 electric sewing-machine motor. Skill in guiding the work is soon 

 acquired. There are some details of a complicated drawing which 

 are more easily cut by the scissors or a knife after the main lines 

 have been cut by the machine." 



497. Contrasting Colors for Marking Groups of Sec- 

 tions. "It is a great advantage in any working model to have sec- 

 tions at regular intervals in marked contrast with the body of the 

 material. Blotting paper of a large variety of colors (black, red 

 blue, pink) is easily obtained in the market. In the models made 

 every tenth plate was a bright or light color and every icoth was 

 black, rendering rapid numeration easy." 



S 498. Putting the Sheets together to Make the Model. 

 " When the paper sections are thus prepared they are piled and 

 replied as is usual until the shape conforms to an outline predeter- 

 mined from photographs, drawings, or measurements made before 

 the specimen was cut." 



' ' It has been found that an easily prepared support and guide 

 for the model in process of setting up, is made by cutting the out- 

 line to be followed from a block of four or five sheets of blotting 

 paper, marking upon it the lines of direction of every tenth or 

 twentieth section. The colored numerating plates must of course 

 conform to the spacing and direction of these lines." 



"The preliminary shaping having been accomplished more 



