Page:Popular Science Monthly Volume 92.djvu/475

 Popular Science Monthly

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��line 1 from the cone base to the apex and also measure line 13 from the cone base to the apex, we, of course, find the line 1 is the longest. In reality we know that

��Pattern

���An approximate sphere in which the section patterns are developed with radial lines f^'9-^

��all the lines from the base to the apex are the same length, but some appear shorter because if they were on a cone made of tin, they would project out towards us and would naturally appear shorter.

If we study Fig. 7 this will be more readily understood. If the line Al-Bl is

���i*-5earn

��The hopper is a good example for showing the pattern development by radial- lines

one of the edges of a triangle lying flat on the paper, all three lines representing the

��three edges will appear in the true length, but if the triangle is turned so that the edge Al-Cl rests on the paper, then the line Al-Bl will be projecting from the paper towards us and the line Al-Bl will appear shorter as in A2-B2. If we were speaking technically we would say the line was "foreshortened," This is the principle back of the method of develop- ing patterns by triangulation which w*ill be taken up soon.

Going back to Fig. 6, we can now see that lines 1 and 9 on the outside of the cone are the only lines that are shown in their true length. To get the true lengths of the other lines on the cone for our pattern, we must draw them over to che left until they strike line 1-apex as shown in the drawing. Then with the apex as a center, swing these lines in an arc until they intersect with the same numbered lines coming up from the arc D-E. To explain this process in a differ- ent way to make it more easily under- stood, run point 1 from the bottom view upward to the base line. Next run points 16 and 2 upward to the hopper line, next over to line l-apex, then in an arc until it strikes line 2 and 16 on the pattern, making a cross at these points. Next run lines 15 and 3 upward to the hopper line, then over to line 1-apex, then in an arc until the arc line intersects lines 3 and. 15, and make a cross at the intersection. Do the same with all the other points oji the bottom view, connect the crosses with a curved line and we will have the line for one side of our pattern. We must now repeat the same process for the other hopper line near "the apex of the cone as is shown in the drawing, and we will have the full pattern for the hopper.

��Deodorizing Benzene for Dry Cleaning Purposes

BENZENE is very useful for the re- moval of grease spots and various other stains. Its odor, however, is very disagreeable to the average housewife. This may be completely removed by re- peatedly shaking up the benzene with a plumbate of soda solution, and rectifying it. The plumbate of soda is made by dissolving litharge in caustic soda.

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