Show HOW TO MAKE ACHROMATIC A-CHROMATIC TOP The chromatic top was so named tao cause It can be used to demonstrate how changes of hue und tone are dependent upon the proportions of the primary colors contained In the solar spectrum Any boy blessed with a clever pair ot hands and an Ingenious turn of mind can become the possessor of one of these little lit-tle wonders by carefully following1 the directions here Riven The fIrst thing that you will require will be a piece of wood about live and a half Inches square by one Inch thick Any hard wood will do but try to obtain ob-tain a piece of beech or linegrained mahogany ma-hogany The wood must be placed on a lathe and turned down to a circular disk l of five Inches In diameter Any carpenter carpen-ter will do this as well as the other work that will have to be done on a lathe for a trifling compensation Then turn a recess threeeighths of an inch deep commencing onornmrtcr of an Inch from the outside edge and leaving a central portion projecting ot half an Inch diameter as at A Fig 1 which la a cross section of the body of the top the dotted lines representing a cross section sec-tion of the disk before the turning Is done don1he The rim of the lop DB and KD Fig 1 can now be turned l 1 down oneeighth of an Inch which will leave It only ono Quarter of nn Inch high and It should then bd curved off nicely as shown at B Fig 1 This side of the body of the top can now be finished off with sandpaper as nothing remains to be done to It The underneath portion however must now be put on thc lathe and be turned to a graceful curve as at BC Fig 1 one quarter of an inch In diameter You can now finish off this side too with sandpaper sand-paper A small hole about onesixteenth of an Inch In diameter should 1 bo drilled through the center A toC ns shown by the dotted line In Fig 1 Now get a small piece of sheet lead oneeighth of an Inch thick and have It turned Into a disk of four and a half Inches diameter with a rpilrnl 1 hole of half an Inch diameter Tnc purpose of this circular disk Is to give weight to the top vand thus make it spin steadily which Is a thing very much to be desired de-sired This disk Is to be placed on the unpcr side of the body of the ton and f It han been turned ncally you will Ind ihnt I 1 K will exactly lit the recess which on had turned In the top Before placing plac-ing It In position however you should lue both the upper part of tho top and the leaden disk llsfilf 1 so that it will holdfast hold-fast when once It has been put In place The body of the ton Is now complete and njl you require is a small wooden lpllHlI1 and two carpenters screws One of the screws should bo about four Inches long and the other two and a half Inches Thf smooth portion of the longer screw should bo about two Inches long as In Fig 2 Measure half an Inch of the screw from whom the plain part left off and then cut off the remainder of the screw so hat I your whole screw will now be about two ami a half Inches long Now lay the screw aside while you turn a small wooden spindle as In Fig 3 ot about half an Inch diameter llnlsh It with sandpaper and drill a hole thviSh It lengthwise of sufficient ulso to allow the plain portion of the screw to revolve easily The spindle should be about two Inches long and one end of It must be countersunk af shown In the dotted lines Fig 3 so that the head of the screw muv lf lint hi It m A liillfi nowdered > blackload should besprinkled be-sprinkled In the hole of the spindle to lubrl rite It Place the screw through It and vHen screw through tho body of the top at A Fig 1 the small hole which you drilled at that point cnabllmr von to screw with lesa likelihood of splitting tho top Do not pcrew so far that thfc spindle will touch tho top and be prevented pre-vented from turning freely The other screw now comes Into use This Is needed for the neg or spindle on which the top spins Cut off the head and fll the remainder of the screw to a bluntlrh point and smooth It on MI oll stom until It is quite polished Thrae nlghths of tho screw portion Is all that is needed find you may therefore out oft the remaining portion Screw It Into Its proper place thfi hole at C Fig 1 first however placing ri little hot glue on It so as to make It hold fast The ton can now be cither nalntrvl or varnished A coat of black paint allowed TO dry hard then sandpapered smooth and finished with another I coat of black looks particularly well Great cnre should bo taken not to allow the paint or varnish to Impede the free working of the spindle spin-dle I dleThe method of spinning the top Is ex tremely simple Wind a piece of string around the power peg hold the top by the wooden spindle and pull the string suddenly I The top will revolve rapidly and with a steady motion Von now proceed to make the color cards which form such an important part of the little contrivance Buy a few sheets of cardboard that known aa Bristol board Is as good as any and with a compass strlks out as many discs four and a half inches In diameter as you can get on me < sheet Cut out each disc with a sharp penknife and I cut u circular hole In the center of each avery a-very small fraction over onehalf Inch In diameter so that It may drop over the central 1 portion A Fig 1 Now procure somn sheets of colored paper red blue yellow etc and cover each card with a colored paper I so that you will have a red card blue card etc Cut each card half through from the central hole to the circumference as shown by the dotted line In Fig l so that yon can slip two cards of different differ-ent colors across each other In such away a-way that only half of each color or any portion of each may be seen when the two are slipped over the central portion of the to Suppose for Instance you place the blue and yellow cards across each other and Hum slip the combined card on the top When the top Is spun you will notice that owing to the velocity of the top the two colors seem blended together formIng form-Ing green and by althcrlng the amount of either color so that more of one card than the other appears various hues between be-tween blue and yellow may be obtained In order that you may mix your colors on a scientific basis you should take a plain card and with a load pencil divide It Into 3GQ parts then fill up the spaces with the colored paper In the following proportions j 15 parts Red 27 parts Orange 43 parts Yellow CO parts Grcert GO parts Bluo 10 parts Indigo SO parts Violet The object > of this card Is to prove that the solar spectrum which Is composed 1 of MO parts distributed as above will bo white Place this card on the top and j you will find that the result of the combination com-bination will be an absolute white The following table shows some of tho colors which can be produced with only e three cards red yellow and blue using two aL a time and in the proportion designated desig-nated Red Yellow Blue Result V < Vz Orange Va V Violet 34 Ji Red orange H Violet red vi Blue violet 1 l l Green I i Yellow groen A vi Green blue |