Popular Science Monthly 



957 



not to melt the aluminum. They should 

 then be stamped between a flat piece of 

 marble, such as a table top, wash bowl top, 

 etc., and a hard flat surface 3 or 4 in. 

 square. A blow of from 10 to 15 lb. with an 

 ordinary hammer is sufficient. Two pieces 

 of marble were used by the author to 

 straighten the disks, with excellent results. 

 The large aluminum plates do not need to 

 be straightened unless badly warped. 



.The small piece of fiber, included in the 

 list of parts, can now be sawed into two 

 i-in. squares, and these drilled through the 

 exact center with the 17/64-in. drill, and 

 then bolted to the 3-in. brass disks, both 

 pieces on one side, so that four J/g-in- holes 

 can be drilled in the fiber to correspond 

 with those in the brass plates near the 

 center. When this is done these four small 

 holes in the brass disks should be counter- 

 sunk with the 17/64-in. drill, on one side of 

 each disk. 



In the exact center of the bottom of the 

 round pasteboard box, mentioned under 

 "materials," a 17/64-in. hole should be 

 urilled, and one of the large brass machine 

 screws inserted from the outside of the box. 

 An extra heavy pasteboard washer 2^ in. 

 in diameter with a 17/64-in. hole in the 

 center, should next be slipped over the 

 machine screw and pushed to the bottom of 

 the box, inside. This washer should be 

 about K-in. thick. It should be followed 

 by two or three of the thin cardboard 

 washers which were not sawed out in the 

 center. 



One of the brass disks can now be slid 

 down on the brass bolt, the side on which 

 the holes were countersunk facing up. 

 Wire nails with their heads removed should 

 next be placed in each of the four counter- 

 sunk holes, points up; also two opposite 

 holes near the circumference should have 

 nails so inserted in them. 



By placing the various disks and washers 

 over the machine screw, and using the nails 

 in the 3^-in. holes as guides, a pile of parts 

 should be built up in the following order: 

 I brass disk, 2 cardboard washers, i small 

 aluminum disk, i cardboard washer, i 

 large aluminum disk, i cardboard washer, 

 I small aluminum disk, etc., ending with the 

 other brass disk, placed countersunk side 

 in, and preceded by 2 washers of cardboard, 

 as at E. 



The four center nails should now be 

 removed, care being taken not to disturb 

 the pile of parts, and the few remaining 

 cardboard washers, with the small center 



holes, placed on the machine screw, and 

 held down tight while a nut is put on the 

 machine screw, and turned down as hard as 

 possible by hand, and one complete turn 

 with pincers. Too much pressure should 

 be avoided, as it is only desired that the 

 parts should be held in place so as to lie 

 flat against each other, without reducing 

 the thickness of the cardboard through 



The mold of wood which is clamped in place for 

 running molten lead over the movable plates 



compression. A quarter sectional view ©f a 

 completed pile is shown at E. 



If all the steps indicated have been 

 properly followed out, there should be a 

 fairly uniform annular space between the 

 pile of disks and the wall of the box. Into 

 this space sufficient melted lead should be 

 poured to cover the complete pile of disks 

 to the top edge of the last piece of card- 

 board after the 2 nails near the edges of the 

 disks have been removed. The molten 

 metal should be heated in two small pans or 

 ladles for a short time after melting, and all 

 scum and dirt removed from the top. 

 When this has been done two streams of 

 melted lead can be poured in simul- 

 taneously, from opposite points near the 

 edge of the round box. 



The lead should be run as quickly as 

 possible without spattering. It must be 

 kept going till the necessary amount has 

 been poured. 



As soon as the lead has cooled the 

 machine screw can be taken out and the 

 complete casting removed from the box. 

 When this has been done the stray pieces of 

 lead can be cut from the top of the pile, so 

 that the cardboard can be removed from the 

 top as well as from the bottom. 



The four nails which were removed from 

 the small center holes should now be re- 

 inserted and melted paraffin should be 

 poured into the 17/64-in. hole in the center 



