The Belt Dynamometer of Doctor C. W. Siemens. By Rob't Briggs, C.E.. figh Railway Speeds. By W. Barnet LeVan... Account of an Experiment Made to betermine the Potential and Economic Vaporization of a Boiler Pogress of the Dephosphorization of Iron. By F. Gantier.. The Involute of the Circumference of a Circle. By L. D'Auria New Pendulum Suspension. By Louis H. Spellier........ The Puddling Process, Past and Present. By Percival Roberts, Jr.. Advantage of Metallic Lubricants, 21. Magnetic and Diamagnetic Elements, 33. American Laureates of the French Academy, 44. Relation of Spectral Rays to the Constitution of Nebulæ, 56. Influ- 63 HOWSON & SON'S OFFICES FOR PROCURING United States and Foreign Patents AND PROSECUTING PATENT CAUSES. HENRY HOWSON, Engineer and Solicitor of Patents. CHARLES HOWSON, Attorney-at-Law and Counsel in Patent Cases. Principal Office, 119 South Fourth Street, Philadelphia. Branch Office, 605 Seventh St., Washington, D.C. Authors of "The American Patent System," "Our Country's Debt to Patents," "Answers to Questions of the State Department Relating to Patents." Also, "Brief Treatise on Patents," published by Porter & Coates. Jan. '80 1 yr. of a RUDOLPH M. HUNTER, M.E., C.E., £3 CONSULTING ENGINEER & SOLICITOR -OF United States & Foreign Expert in the Trial of Patent Causes. Examinations in regard to the Validity and Infringement of Patents. Offices, Rejected Cases a Specialty. 901 Walnut St., Dec.. '79 Lyr PHILADELPHIA. |