11.* On the Present State of the Question of Standards of Length. By W. A. ROGERS. (Proc. Am. Acad. of Arts and Sciences, XV. 273.) * 12. Dimensions of the Fixed Stars, with especial Reference to Bi- 13. Description of a New Position Micrometer. By LEONARD WALDO. (Am. Journ. of Science and Arts, July, 1880; 3d 14. On Tolles's Interior Illuminator for Opaque Objects. By W. A. 15. The Coefficient of Safety in Navigation. By W. A. Rogers. (Proc. U. S. Naval Institute, VII. Nos. 3 and 4. Science, April, 16. On the Conditions of Success in the Construction and the Com- parison of Standards of Length. By W. A. ROGERS. (Proc. Am. Soc. Micros., 1882, p. 231.) 17.* New Planetary Nebulæ. By EDWARD C. PICKERING. (Am. Journ. of Science, Oct. 1880; CXX. 303. The Observatory, 18.* Thirty-fifth Annual Report of the Director of the Astronomical Observatory of Harvard College, presented to the Visiting Committee Dec. 6, 1880. (Cambridge, 1881. 8vo.) 19.* Variable Stars of Short Period. By EDWARD C. PICKering. (Proc. Am. Acad. of Arts and Sciences, XVI. 257. The Observatory, Aug.-Oct. 1881; IV. 225, 264, 284.) 20.* Large Telescopes. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XVI. 364. Nature, Aug. 1881; 21.* Photometric Measurements of the Variable Stars B Persei and DM. 81° 25, made at the Harvard College Observatory. E. C. PICKERING, ARTHUR SEARLE, and O. C. WENDELL, Ob- servers. (Proc. Am. Acad. of Arts and Sciences, XVI. 370.) 22.* Report of the Committee on Standards of Stellar Magnitude. (Proc. Am. Assoc. for Advancement of Science, 1881, 23.* On a Convenient Method of Expressing micrometrically the Re- same Scale. By W. A. ROGERS. (Proc. Am. Assoc. for Ad- vancement of Science, 1881; XXX. 116.) 24. Thirty-sixth Annual Report of the Director of the Astronomical Observatory of Harvard College, presented to the Visiting Committee Nov. 10, 1881. (Cambridge, 1882. 8vo.) 25.* Geodetic Formulæ. By J. RAYNER EDMANDS. (Appalachia, 26.* A Plan for Securing Observations of the Variable Stars. By EDWARD C. PICKERING. (Cambridge, 1882. 8vo.) 27. On a Method of Reducing Different Catalogues of Stars to a Homogeneous System. By W. A. ROGERS. (Proc. Am. Assoc. for Advancement of Science, 1882; XXXI. 99.) 28. On the Performance of a New Form of Level invented by Mr. John Clark of the U. S. Coast Survey. By W. A. ROGERS. (Proc. Am. Assoc. for Advancement of Science, 1882; XXXI. 29. A Study of the Problem of Fine Rulings with Respect to the Limits of Naked Eye Visibility and Microscopic Resolution. By W. A. ROGERS. (Am. Monthly Microscopical Journal, 30.* Statement of Work done at the Harvard College Observatory during the Years 1877-82. By EDWARD C. PICKERING. 31.* Thirty-seventh Annual Report of the Director of the Astro- nomical Observatory of Harvard College, presented to the Visiting Committee Nov. 22, 1882. (Cambridge, 1883. 32. First Circular of Instructions for Observers of Variable Stars, acting in Co-operation with the Harvard College Observatory, 33. The Wedge Photometer. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XVII. 231.) 34. Observations of the Transit of Venus, Dec. 5 and 6, 1882, made 36. Studies in Metrology. By W. A. ROGERS. (Proc. Am. Acad. of Arts and Sciences, XVIII. 287.) 37. On the Reduction of different Star Catalogues to a Common System. By W. A. ROGERS. (Proc. Am. Acad. of Arts and Sciences, XVIII. 399; Astronomische Nachrichten, CVI. 257.) 38.* Second Report of the Committee on Standards of Stellar Magnitudes. EDWARD C. PICKERING, Chairman. (Proc. Am. Assoc. for the Advancement of Science, XXXII. 1.) 39.* Mountain Observatories. By EDWARD C. PICKERING. (Appalachia, III. 99. The Observatory, VI. 287.) 40.* A Critical Study of the Action of a Diamond in ruling Lines upon Glass and Metals. By W. A. ROGERS. (Proc. Am. Soc. of Microscopists, XXXII. 149.) 41.* A Study of the Centimeter marked " A," prepared by the U. S. Bureau of Weights and Measures for the Committee on Micrometry. By W. A. ROGERS. (Proc. Am. Soc. of Microscopists, XXXII. 184.) 42.* Vice-President's Address on the German Survey of the Northern Heavens. By W. A. ROGERS. (Proc. Am. Assoc. for the Advancement of Science, 1883; XXXII. 53.) 43. The Zodiacal Light. By ARTHUR SEARLE. (Proc. Am. Acad. of Arts and Sciences, XIX. 146.) 44. Researches upon the Photography of Planetary and Stellar Spectra, by the late HENRY DRAPER. Results of Measure ** ments, by E. C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XIX. 231.) 45. Thirty-eighth Annual Report of the Director of the Astronomical Observatory of Harvard College, presented to the Visiting Committee Dec. 19, 1883. (Cambridge, 1884. 8vo.) 46.* Sir William Herschel's Observations of Variable Stars. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and 47.* Recent Observations of Variable Stars. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XIX. 296.) 48. The Phases of the Moon. By ARTHUR SEARLE. (Proc. Am. Acad. of Arts and Sciences, XIX. 310.) 49.* Light of Comparison Stars for Vesta. By EDWARD C. PICK(Am. Journ. of Science, CXXVIII. 17.) ERING. 50. On a Practical Solution of the Perfect Screw Problem. By W. A. ROGERS. (Trans. of the Am. Soc. of Mechanical Engineers, Vol. V.) 51.* Thirty-ninth Annual Report of the Director of the Astronomical Observatory of Harvard College, presented to the Visiting Committee Dec. 17, 1884. (Cambridge, 1885. 8vo.) 52. On the Determination of the Absolute Lengths of Eight Rowland Gratings. By W. A. ROGERS. (Proc. Am. Soc. Micros. 1885, p. 151.) 53.* The Microscope in the Workshop. By W. A. ROGERS. (Proc. Soc. of Mechanical Engineers, Boston Meeting, 1885, p. 1.) 54.* An Examination of the Standards of Length constructed by the Société Génevoise. By W. A. ROGERS. (Proc. Am. Acad. of Arts and Sciences, XX. 379.) 55. Observations of Variable Stars in 1884. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XX. 393.) 56. A Photographic Study of the Nebula of Orion. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XX. 407.) 57. A Preliminary Examination of Metal Thermometers. By W. A. ROGERS. (Am. Meteor. Journ., Oct. 1885, p. 252.) 58. Description of a Series of Fifty Slides, illustrating the Action of a Diamond in Ruling upon Glass, presented to the Royal Microscopical Society of London. By W. A. ROGERS. (Journ. Roy. Micros. Soc., Oct. 1885.) 59. On a New Form of Section-Cutter. By W. A. ROGERS. (Proc. Am. Soc. Micros., 1885, p. 191.) 60. On the Original Graduation of the Harvard College Meridian Circle, in Situ. By W. A. ROGERS and GEO. B. CLARK. (Proc. Am. Assoc. for the Advancement of Science, 1884; XXXIII. 111.) 61. Additional Observations confirming the Relation: Mètre des Archives = Imperial Yard +3.37027 inches. By W. A. ROGERS. (Proc. Am. Assoc. for the Advancement of Science, 1884; XXXIII. 117.) 62. Early Experiments in Telegraphing Sound. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XXI. 262.) 63.* Atmospheric Refraction. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XXI. 268.) 64.* A New Form of Polarimeter. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XXI. 294.) 65.* Observations of Variable Stars in 1885. By EDWARD C. PICK(Proc. Am. Acad. of Arts and Sciences, XXI. 319.) 66.* Third Report of the Committee on Standards of Stellar Magnitude. EDWARD C. PICKERING, Chairman. (Proc. Am. Assoc. for the Advancement of Science, 1885, XXXIV. 1.) * 67. Possibility of Errors in Scientific Research due to Thought Transference. By EDWARD C. PICKERING. Psychical Research, I. 235.) (Am. Soc. 68.* Fortieth Annual Report of the Director of the Astronomical Observatory of Harvard College, presented to the Visiting Committee Dec. 3, 1885. (Cambridge, 1886. 8vo.) 69.* A Plan for the Extension of Astronomical Research. By EDWARD C. PICKERING. (Cambridge, 1886.) 70. Report on the Investigation of the Units of Length employed by the Pratt and Whitney Co. By W. A. ROGERS. 1886. 71. International Electrical Exhibition, 1884. Report of SubCommittee on Railway Signals. W. A. ROGERS, Chairman. 1886. 72.* Accurate Mountain Heights. By EDWARD C. PICKERING. (Appalachia, IV. 215. Science, VII. 423.) 73.* Comparison of Maps of the Ultra Violet Spectrum. By EDWARD C. PICKERING. (Am. Journ. of Science, CXXXII. 223.) 74.* Heights of the White Mountains. By EDWARD C. PICKERING. (Appalachia, IV. 305.) 75. Forty-first Annual Report of the Director of the Astronomical Observatory of Harvard College, presented to the Visiting Committee Dec. 7, 1886. (Cambridge, 1887. 8vo.) 76.* Observations of Variable Stars in 1886. By EDWARD C. PICKERING. (Proc. Am. Acad. of Arts and Sciences, XXII. 380.) 77.* Harvard College Observatory. Form of Records. 78. Forty-second Annual Report of the Director of the Astronomical |