Show HE GAIN CAN BEND STEEL CAR BAR FIVE INNS INCHES n kj IETER but hes no strong man demonstrates efficiency of ceasur ing instruments new york A man mail of ordinary strength can bend a steel hiir bar live inches in diameter lie ie can do it by exerting only SO 30 pounds pressure to he be sure lie cannot bend the bar double ilo uhle fur far from froin it chester T crowell mo performed the feat explains in tile hie north american review that when hen lie tried ills his strength lie moed them bar about rhe fhe millionths of nn an inch lie ho recounts the bending exercise as an instance of tile remarkable advance that his has been made to ID the accuracy of instruments of measurement there are now quite a large number of machines performing utilitarian service comparable L to 10 day labor that mut must be acau accurate rate at least in some of their parts three or four hundred thousandths of an inch a requirement that was anas unthinkable only it a generation or to ago lie be says and there tire are many hundreds of gauges in fit use in this country alone that must be accurate within a few millionths of an all inh the measurement of the bond bend in the five inch steel bar lie he explains was possible by tile the use of light rays such accurate measurements are not impractical wanderings in science let us assume says crowell Cro that that the luch ilich bar of steel was destined des lined for use as a shaft in fit some machine designed to generate limi power er it must carry a heavy strain and at the same time it must fit other parts of the maebane machi nei within certainly five dvo ten thou abou of an inch under working orld ng condit conditions lons A variation of one ne flie thou sanath of nn an inch beyond the margin of safety would me mean in friction land a hor horrible lio nible tible explosion clort of the modern types of pov power er generah ins ing machinery m move 0 ve nt at such unimaginable speet speeds Is that if anything should go wrung wrong and friction result in metal would become incandescent in a few minutes any newspaper realer reader knows that such accidents simply dont happen now a days unit and most or of us have forgot ten that once they lid did happen at least occasionally tile art 0 of calibration Is now so nall ell advanced that an ordinary shop ork inspector would very q slickly spot an error of alve hud him dred thousandths of an inch and refuse to 0 T K tile the defective part the human eye and the human ennd also ure are developing amazing ability abili tv in accurate measurement croell sais in his north amerl ameri can review article lie tells of one e factory In inspector who detected an 1 error of one thousandth a of at an inch in a gauge simply by the feel of it |