| Show MEASURES OF INCH new apparatus of english invention that will determine extremely minute distances distance the extreme delicacy ot of scientific in measurement easu rement Is shon by an apparatus ot of english invention for or comparing official standards 0 of length its action depends upon tue tile interference of light waves causing shadow bands tho the width ot of which Is halt half the wave length of 0 the light employed the red radiation from hydrogen or cadmium Is used and its wave length is say the BO 50 lomoth 0 of an inch the machine carries two microscopes one ot of which Is attached to ono one of 0 tile the glass plates reflecting the light and producing the interference bands first the recognized standard rod say the imperial standard yard Is placed under tile lie two microscopes and one of of Us its terminal marks is brought under the spider lines ot of each then tile the rod to be tested Is substituted and one of 0 its ita terminals Is accurately adjusted it if it varies from the of the standard tho the other microscope carry I 1 ing the reflector must be shifted until coincidence ti ta the number of 0 bends bands that ni pvc past during the shifting by the halt bait wavelengths wave lengths A 1 the light gives tho the difference in length afif it the rods acl fi Anic rican |
