Popular Science Monthly 



459 



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. 



