{Herbert Dingle [lecture & notes by FHS on "Science and the Unobservable"]; Harold B. Dirks; Roberta Lloyd [Mrs. Hugh T.] Dobbins [re S. Pike's grave]; Dorpat University Meteorological Observatory; E. Doublet; John C. Duncan; R. S. Dugan; Theodore Dunham, Jr.; Theodore Dufur; O. L. Dustheimer}
{C. Easton; J. M. Eder; Frank K. Edmondson; W. S. Eichelberger; Greta Ekelöf; Ferdinand Ellerman [ltrs re FE's death: George E. Johnson ? FHS; FHS ? GEJ]; C. T. Elvey; Pio Emanuelli; Encyclopaedia Britannica [W. L. Dalton]; S. Enebo; Wilhelm Engelman, Publisher; Eugene H. Eyster}
{Nikolayev Astronomical Observatory [L. Semenov]; Nixdorf Observatory; Charles A. Noble; Gladys Noon; H. Nort; Norwegian Meteorological Institute [folded]; Werner Nowachi; Arthur A. Noyes}
{Albert Chase McArthur; Macbeth Daylighting Co., Inc. [Norman Macbeth]; Lucena McBride; Phoebe Merl McClees [ltrs M. E. Churchill ?? FHS; FHS ? Fisk Teachers' Agencies]; Frank McCoy; E. C. MacDowell; Anita Newcomb McGee; McGill University; Dean B. McLaughlin; MacMillan Co. Publishers [Rose Levy]; Mrs. John McMillan; Maud W. Makemson; E. Mallinckrodt, Jr.; Marburg University Library; Marchaut Calculating Machine Co. [folded]; W. L. Marcy; Marina, Instituto y Observatorio de; Marquis, A. N. & Co.}
{R. A. Millikan; Monroe Calculating Machine Co. [folded. incl Calculator Equipment Corp.]; Montevideo, Observatory of the University of [folded]; Monthly Weather Review; Joseph Monti; K. Moór [?]; Ernest C. Moore; Morava Construction Co.; D. W. Morehouse [incl ltr H. Shapley ? DWM]; D. P. Moreton; G. W. Morey; --Moriceau; T. H. Morgan; Sylvanus G. Morley; W. D. Morrison; Albert G. Mowbray [incl memo EPH ? FHS]; F. R. Moulton; Z. Müller; Carlos S. Mundt}
{J. Jackson; Harold Jacoby; Hamilton M. Jeffers; Frank B. Jewett; N. Jewdokimow; Johns Hopkins Press/University; William Templeton Johnson; Robert Jonckheer; T. T. Jones Co.; Frederick C. Jordan; L. V. Julihn [incl ltr F. G. Cottrell ? FHS]; W. Junk, Publishers}
{J. O. Backlund; Solon Irving Bailey; L. D. Bailiff; Baker & Taylor Co.; Bakersfield Californian; E. F. van de Sande Bakhuyzen; Ruth S. Bakker; A. C. Balch; Ralph R. Baldwin; P. Barrachi; Martha Barnum; John Barrett; Albert Lloyd Barrows}
