Scientific Works published by Longmans, Green, <5^ Co, 21 ASTRONOMY, NAVIGATION, ETC. Continued. GILL, TEXT-BOOK ON NAVIGATION AND NAUTICAL AS- TRONOMY. By J. GILL, F.R.A.S. New Edition Augmented and Re-arranged by W. V. MERRIFIELD, B.A. Medium 8vo., los. 6d. net. HERSCHEL. OUTLINES OF ASTRONOMY. By Sir JOHN F. W. HERSCHEL, Bart., K.H., etc. With 9 Plates and numerous Diagrams. 8vo. . i2s. LAUGHTON.AN INTRODUCTION TO THE PRACTICAL AND THEORETICAL STUDY OF NAUTICAL SURVEYING. By JOHN KNOX LAUGHTON, M.A., F.R.A.S. With 35 Diagrams. Crown 8vo., 6.r. MAXTIN. NAVIGATION AND NAUTICAL ASTRONOMY. Compiled by Staff Commander W. R. MARTIN, R.N. Royal 8vo., i8s. MERRIFIELD. A TREATISE ON NAVIGATION. For the Use of Students. By J. MERRIFIELD, LL.D., F.R.A.S., F.M.S. With Charts and Diagrams. Crown 8vo. , $*. PARKER. ELEMENTS OF ASTRONOMY. With Numerous Ex- amples and Examination Papers. By GEORGE W. PARKER, M.A. , of Trinity College, Dublin. With 84 Diagrams. 8vo. , $s. 6d. net. WEBB. CELESTIAL OBJECTS FOR COMMON TELESCOPES. By the Rev. T. W. WEBB, M.A., F.R.A.S. Fifth Edition. Revised and greatly Enlarged by the Rev. T. E. ESPIN, M.A., F.R.A.S. (Two Volumes.) Vol. I., with Portrait and a Reminiscence of the Author, 2 Plates, and numerous Illustrations. Crown 8vo., 6s. Vol. II., with numerous Illustrations. Crown 8vo., 6s. 6d. WORKS BY RICHARD A. PROCTOR. THE MOON : Her Motions, Aspect, Scenery, and Physical Condition. With many Plates and Charts, Wood Engravings, and 2 Lunar Photographs. Crown 8vo., y. 6d. OTHER WORLDS THAN OURS : the Plurality of Worlds Studied Under the Light of Recent Scientific Researches. With 14 Illustrations; Map, Charts, etc. Crown 8vo., 3^. 6d. OUR PLACE AMONG INFINITIES : a Series of Essays contrasting our Little Abode in Space and Time with the Infinities around us. Crown 8vo., 35. 6d. MYTHS AND MARVELS OF ASTRONOMY. Crown 8vo., 3*. 6d. LIGHT SCIENCE FOR LEISURE HOURS: Familiar Essays on Scientific Subjects, Natural Phenomena, etc. Crown 8vo., 35. 6d. THE ORBS AROUND US; Essays on the Moon and Planets, Meteors and Comets, the Sun and Coloured Pairs of Suns. Crown 8vo. , 35. 6d. THE EXPANSE OF HEAVEN : Essays on the Wonders of the Firmament. Crown 8vo. , 35. 6d. OTHER SUNS THAN OURS: a Series of Essays on Suns Old, Young, and Dead. With other Science Gleanings. Two Essays on Whist, and Corre- spondence with Sir John Herschel. With 9 Star-Maps and Diagrams. Crown 8vo., 3-r. 6d. HALF-HOURS WITH THE TELESCOPE : a Popular Guide to the Use of the Telescope as a means of Amusement and Instruction. With 7 Plates. Fcp. 8vo. , 2s. 6d. OVER.