Open main menu

Page:Popular Science Monthly Volume 89.djvu/450

This page needs to be proofread.


436

��Popular Science Mont/ili/

��A Fascinating Old Sport in a New Dress

AN inlerestiiig outdoor game may!«■ evolved from the simple act of tossing a wooden spear at a moving ring. A conveniently located tree, f)r a cross- arm of scantling may be used to suspend it. The rope is tied to the cleat C and passes through sev- eral eyes or guides. At the end, the small stick

���The Ring Is Set Swinging and the Spear Is ToEsed Through It From a Distance

B is tied. The ring ^ is a piece of spring wire which snaps on to the stick. The spear is a broom-handle or straight pole with one sharp end. The ring is set swing- ing with a gentle penrlulum-like motion and the one about to test his skill endea\ - ors to toss it through. If it touches the ring another trial is allowed, and if it passes through cleanly ten points are scored. As skill increases the throwing dis- tance may be lengthened. After passing through the ring one point is scored for every five feet the spear travels. If it is of this length it will be easy to measure and count the points. The sport is fascinating and admits of nnich variation in scoring.

Tracing Magazine Cuts

THE cut is traced on a clean, unused sheet of carbon paper with a sharp pencil. The j)rii]ts are then made from the carbon sheet; they will be blue lines on a white background. By this method it is possible to pencil additional notes on to the print. The carbon sheets can be used as long as necessary and then renewed by holding them against anv hoi surface such as an electric globe. This will melt the c.irbon preparation and soon cover all the lines.

��Measuring Ten Thousandths of an Inch

THK accompanying illustration shows the essential parts of a micrometer designed to indicate on a scale S the thickness, in thousandths of a millimeter (one millimeter is about one twenty-fifth of an incli) of any small object placed between two tempered steel blocks, 5, and B2-

\n using the instrument the blocks Bi Bo are first brought together without obstacle, and then the micrometer screw is turned in one direction or the other until / stands at zero on .S. A button is then pressed to turn the lever about the pivot A and permit introduction of the body to be measured between Bi B^. The screw T is then rotated as far as neces- sary to make the spring e.xert a suitable pressure on the piece between B^ B2.

Between the block B^ and a fixed block C there is stretched a wire between the centi-r point of which and a second

���N=<C3

��Esr.cntial Parts of a Micrometer That In- dicates Thickness in Thousandths of a Milhmeter on a Finely Balanced Scale

block E there is stretched a second wire DE. The wire FG is attached to the center of DK and, after i>assing round a pulley P on the point spindle it (FG) is anchored to a plate spring K. The latter keeps taut the wires GF, ED and B-, (', hence as B2 moves to the left (when a |)iece to be measured is intro- ducetl between B^ Bo or the zero of the instruments is adjusted), the slack in Bo C is taken up by the sag of the wire being increased. Slack thus produced in I')!', is taken u|) by incri'ased sag at /•', the spring A' meanwhile "nn)ving to the Kll to take up slack in FG.

�� �