296 



Popular Science Monthly 



section C so that we can get the correct 

 widths down to the front view. The arcs 

 D and E are swung up to the line F and 

 then dropped down (see dotted lines) until 

 they strike the edge of the sphere on the 

 front view, as indicated by the crosses. 

 Next, run the lines D and E across the 

 front view. Then drop the dotted lines 

 from D and E on the top view down until 

 they cross the lines D and E on the front 

 view. Connect these crosses with a 

 curved line and you have the true front 

 view of the section C. 



Developing the Pattern 



The development of the pattern for the 

 section is as follows: First, draw the 

 cylinder G, Fig. 2, 

 with its bottom 

 view H. Draw 

 the section C on 

 the cylinder the 

 same size as sec- 

 tion C on the top 



Fiq4 



i Pattern 



Another interesting 

 method of developing 

 the same pattern 



view of Fig. 1. Now, if the rectangle 

 K-L-M-N, Fig. 2, is thought of as repre- 

 senting the front view of a cylinder, 

 or round pipe, it will be seen that the 

 section C is simply a slice of that cylin- 

 der. After this is seen, the problem 

 becomes a very simple one in which we 

 use exactly the same methods of develop- 

 ment as we used in the elbow pat- 

 terns. Second, draw the bottom view 

 //. Divide one-half into eight equal parts. 

 We only use one half because the section 

 only runs half way round the cylinder. 

 Third, draw the base line 0-P, obtaining 

 the correct length by stepping off the 

 eight spaces from the bottom view //. 

 Run the lines from the points on the 

 bottom view upward until they strike the 

 section C. Then run them over until 



they intersect the same numbered line 

 coming up from the base line 0-P. Make 

 a cross at the point of intersection and 

 connect with a curve. Then you have the 

 complete pattern for the section C. Cut 

 out sixteen of these. Bend them to the 

 form of a half circle and solder them to- 

 gether. No allowance is necessary for 

 laps or seams. 



A "short cut" method is shown in Fig. 

 3, in which the top view corresponds to 

 G in Fig. 1. No bottom view is needed 

 because the lower half is used as the 

 bottom view, and the section division 

 lines designate the bottom view points. 

 Lay off the base line S-T by stepping off 

 the distance as numbered. Run the lines 

 upward until they strike section C; then 

 over to the right until they cross the same 

 numbered lines coming up from the base 

 line. Mark the intersection with a cross. 

 Connect these crosses with a curve, and 

 you will have one-half of the pattern. 

 By repeating this operation farther along, 

 the entire pattern may be developed. 



A Simple Method of Developing 

 the Pattern 



Another interesting method of develop- 

 ing this pattern is shown in Fig. 4. It 

 will be seen that the drawing of the top 

 view and the front view is the same as in 

 Fig. 1. The steps taken are: First, 

 draw the top view U. Second, divide 

 section C into any number of parts, as 

 numbered from 1 to 6. These are swung 

 around to line W; then dropped down to 

 the front view circle; then across to sec- 

 tion C. Third, drop the lines down from 

 section C, top view until they cross the 

 same numbered lines running across sec- 

 tion C, in the bottom view. Mark with 

 crosses and connect with a curved line. 

 This will give the correct front view of 

 section C. Now draw the line X- Y. 

 Get the correct length by stepping off the 

 distances, as indicated by the same num- 

 bers on the circle. Then with the 

 compasses, measure the width of section 

 C, front view, line one, and set off the 

 same width on line one of the pattern. 

 Do the same with the other lines and you 

 will have the pattern for one-half of 

 section C'. After the pattern is developed 

 it is an easy matter to build up the ball, 

 making an almost perfect sphere in the 

 completed ornament. 



