936 



Popular Science Monthly 



the same numbered lines, then make a 

 cross, connect these crosses with a free- 

 hand curve and the one-quarter pattern 

 is complete. 



The illustration (Fig. 2) shows the meth- 

 od of developing the pattern for a bath 



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A pattern for a bathtub is developed in 

 a similar manner to a hopper and pipe 



tub. Notice that the tub is made up of 

 five parts, bottom, two ends and two 

 sides. The pattern for the bottom needs 

 no development as the top view, A, gives 

 us a true pattern. The patterns for both 

 ends and one side must be developed in 

 exactly the same manner as that described 

 for Fig. 1, and will not be repeated here. 

 Notice that it is one-half of a cone and 

 developed in the same manner as for the 

 hopper and pipe. 



The pattern for the end, C, is developed 

 in the same manner, except that the base 

 circle has been drawn downwards instead 

 of upwards as was done on end view B. 

 This method is often used and was intro- 

 duced here so that the students of this 

 series might become familiar with it. 

 The base circle is divided and the points 

 projected to the base line, then to the 

 apex in the usual manner. The points 

 where the radial lines from base to apex 

 cross the curved line of the tub are pro- 

 jected over to line apex-1 and then swing 

 across the pattern until they cross the 

 same numbered lines in exactly the same 

 manner as described for previous prob- 

 lems. 



The pattern for the side, 1), is easily 

 drawn. The correct width is obtained 



from D front view. The height is not 

 correct on the front view because the top 

 edge is leaning towards us. The correct 

 height is obtained from the line, 1-X. It 

 is the same height as the side, D, and has 

 the same angle of inclination or slant, 

 therefore, the line, 1-X, is the true height 

 of the side, D. Set off the width from D 

 and the height, 1-X, and the pattern for 

 all parts is complete. Allowance must 

 be made on these patterns for seams, and 

 wiring as shown in previous issues. 



The illustration (Fig. 3j shows the de- 

 velopment of patterns for an "egg 

 tester." A lighted candle is placed inside 

 and the eggs are held against the egg- 

 shaped hole. This must be done in a dark 

 room. If the egg is clear and transparent 

 it is fresh; if cloudy it is old. If it shows 

 a dark spot, the process of incubation has 

 started. The V-shaped hole at the bottom 

 is to admit air so that the candle will burn 

 brightly. 



The technical description of the prob- 

 lem would be "development of pattern 

 for a cylinder intersecting a truncated 

 cone." As stated before, these terms are 

 often confusing to the non-technical 

 reader, but advanatge should be taken 

 of every opportunity to become familiar 

 with them. 



The development of the pattern for the 

 round pipe (cylinder) has been described 

 so many times in various ways in this 

 series that no further description is 

 deemed necessary, neither is it shown in 

 the drawing. The best explanation will 

 be found in the December, 1917, issue, 

 "Development of Pattern for Tee Joints." 

 The egg-shaped hole is drawn freehand. 



The development of the pattern for the 

 cone gives us an opportunity to review the 

 use of auxiliary points and to make use 

 of a still different method of drawing the 

 bottom view and base line circle. The 

 steps taken are as follows: First, draw 

 front view A and side view B. Second, 

 complete the cone by continuing the side 

 lines until they meet at the "apex." 

 Third, draw the bottom view, that is the 

 circle on the base line. Notice that this 

 is the first time that we have drawn the 

 full circle on the base line. In previous 

 issues it has been dropped down some 

 distance from the front view to avoid 

 confusion, but it is now time that we 

 become acquainted with these different 



