Permits measurement of refractive indices of liquids, transparent and translucent solutions and solids. Measurable range extends from 1.300 to 1.700 accuracy 0.001 by direct reading and 0.0001 by estimation finely marked glass translucent arc scale permits measurements of dispersion water jacketed prism box: allows measurement of index of refraction at the desired temperature. Compensator consisting of amici prism : allows to compensate for dispersion thus making it possible to have a fine critical line.