The instrumentation for the magnetic focusing and analysis of the external beam of the Michigan cyclotron is described. It provides to a scattering chamber in an adjacent room a beam of deuterons of a few tenths microampere monoenergetic to within 15 kev at a mean energy of 7.8 Mev. A double‐focusing analyzer magnet of mean radius one meter, focuses reaction products of magnetic rigidity less than or equal to that of a 20‐Mev proton. At the optimum energy resolution of the system, proton groups from (d,p) reactions differing inQby about 20 kev can be resolved. Particles can be observed over a continuum of angles from −7° to +112° relative to the incident beam. The determination of reaction energies and the measurement of relative differential cross sections are discussed.