VII. MISCELLANEOUS.--Cold Storage for Potatoes.--The application of artificial cold to preserving potatoes.--Results obtained in actual experience.--A practical paper by Mr. EDWIN TAYLOR. 10115 VIII. PHYSICS.--On a Method of Making the Wave Length of Sodium Light the Actual and Practical Standard of Length.--By ALBERT A. MICHELSON and EDWARD W. MORLEY.--Description of the new standard of length and outlines of the practical method for its determination.--The question of check determinations. 1 illustration. 10115 IX. TECHNOLOGY.--Progress of the Sorghum Sugar Industry.-- Elaborate report on the diffusion process as developed at the Fort Worth, Kan., station. 2 illustrations. 10110 The Lowe Incandescent Gas Burner.--The well known advanced type of gas burner described and illustrated. 1 illustration. 10110 * * * * * THE COMPOUND STEAM TURBINE. Last year the whole of the lighting of the Newcastle Exhibition was effected by the agency of seventeen of these motors, of which four were spare, giving in the aggregate 280 electrical horse power. As the steam was provided by the authorities of the exhibition, it was good proof to the public that they had satisfied themselves that the consumption would not be extravagant, as however favorable might be the terms on which the manufacturers would be willing to lend their engines, they could scarcely be sufficiently tempting to compensate for an outrageous consumption of coal, even in Newcastle. At the time we gave an account of the result of the test, showing that the steam used was 65 lb. per electrical horse power, a very satisfactory result, and equal to 43 lb. per indicated horse power if compared with an ordinary engine driving a generator through a belt. Recently Mr. Parsons has given an account of the theory and construction of his motor before the Northeast Coast Institution, and has quoted 52 lb. of steam per electric horse power as the best result hitherto attained with a steam pressure of 90 lb. As now made there are forty-five turbines through which the steam passes in succession, expanding in each, until it is finally exhausted. [Illustration: THE COMPOUND STEAM TURBINE.] The theoretical efficiency of a motor of this kind is arrived at by Mr. Parsons in the following manner: