{Clara Robinson; Ruth Stone [Mrs. C. C.] Robinson; Rev. Luis Rodés, S.J.; Guy Rose; H. Rosenberg; Royal Institution, London; Royal Society of Edinburgh; Royal Society of London; Walter Russell; Ryerson Physical Laboratory; P. M. Ryves}
{Dorothy N. Davis; Dartmouth College, Baker Memorial Library; L. P. Delsasso; Denver Public Library; Debrecen University Physical Institute; Rev. C. E. Deppermann, S.J.; Detroit Public Library; Deutsche Physikalische Gesellschaft; Deutsches Museum; L. E. Dickson}
{California State Library; José da Silveira Camerino; Francis A. Campbell; Léon Cap; R. Stanley Capon; Ellsworth Carpenter; F. E. Carr; Carter Observatory [R. C. Hayes]; S. Chapman; Rev. Stanislaus Chevalier, S.J.; Christian Science Monitor [Robert K. Shellaby]; Christiania University Observatory}
{Aug. Collard; T. Collodi; F. Barrows Colton; Commission for Russian Scientists; A. Pribar de Conill; Duvall Cooper; Copernicus 450th Anniversary; Corning Glass Works; A. L. Cortie, S.J.; Robert Coughran; G. Cramer Dry Plate Co.; R. T. Crawford; Henry Crew; Raymond E. Crowtherb [Kodak, London]; James Cuffey}
{Fr. R. Cirera, S.J.; Cpt. P. Civalleri, R.I.N.; Civic Bureau of Music and Art of Los Angeles; Claremont Colleges; Nell Ray Clarke; --Clasen; Gerald Coffman}
{Herbert Meredith Reese; F. P. Reilly; M. dos Reis; W. Reiter; Remeis Observatory, Bamberg; Rennselaer Polytechnic Institute Library; Republic Productions, Inc. [John T. Bourke]; D. J. Rhederg; E. W. Rice; Hugh S. Rice; C. R. Richards; Harold Richards; L. J. Richardson; R. G. D. Richardson; K. M. Richey}
{Joseph A. Hodam; C. Hoffmeister; Helen Sawyer Hogg; Melvin J. Hoirch; Hong Kong Royal Observatory; Inga Howard; Herbert A. Howe; J. Huizinga; Beatrice M. Humason; W. J. Hussey; Robert Maynard Hutchins}
