{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}
{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}
{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}
{Oberlin College [F. E. Carr; Emma L. Frank]; Sir Frederick O'Connor; J. Ogden; R. M. Ogden; Yngve Öhlman; Eleanor Olney; John Ohlsson; William Tyler Olcott [& G. H. Lutz]; Charles P. Olivier; P. Th. Oosterhoff; Earle L. Ovington}
{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}
{Barthet's Laboratory & Observatory; Raymond Bartholomew; William H. Barton, Jr.; Bautzen Observatory; Ernest H. Beattie; Wilhelm Becker; Otto Behrens; Belgium, Royal Observatory of; S. Beljawsky; Bell System Technical Journal; F. A. Bellamy; Andrew P. Beltran; Raine Bennett; Junior B. Benton; Berlin University Observatory; E. Bianchi; Claude R. Bird; Raymond Thayer Birge; Charles Bittinger; Vilhelm Bjerknes; Philip E. Bliss}
{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}
