Scientific Works published by Longmans, Green, & Co. n GEOMETRY AND EUCLID.

%* For other Works, see Longmans &" Co.'s Catalogue of Educational and School Books. ALLMAN. GREEK GEOMETRY FROM THALES TO EUCLID. By G. J. ALLMAN. 8vo. , los. 6d. BARRELL. ELEMENTARY GEOMETRY. By FRANK R. BARRELL, M.A., B.Sc., Professor of Mathematics, University College, Bristol. Section I. Part I., being the subject-matter of Euclid, Book I. Crown 8vo., is. Section I. Part II., containing the subject-matter of Euclid, Book III. 1-34, and Book IV. 4-9. Crown 8vo. , is. Section I. complete. Crown 8vo. , 2s. Section II., containing the remainder of Euclid, Books III. and IV., together with the subject- matter of Books II. and VI. With explanation of Ratio and Proportion, Trigono- metric Ratios and Measurement of Circles. Crown 8vo. , i s. 6d. Sections I. and II. in one volume. Crown 8vo., y. 6d. Section III., containing the subject-matter of Euclid, Book XI., together with a full treat- ment of volume and surface of the cylinder, cone, sphere, etc. Crown 8vo., is. 6d. Sections I., II. and III. complete in one volume. Crown 8vo., 45. 6d. CASY. Works by JOHN CASEY, LL.D., F.R.S. THE ELEMENTS OF EUCLID, BOOKS I. -VI. and Propositions, I.-XXI. of Book XL, and an Appendix of the Cylinder, Sphere, Cone, etc. With Copious Annotations and numerous Exercises. Fcp. 8vo., 4^. 6d. KEY to Exercises. Fcp. 8vo., 6s. A SEQUEL TO THE ELEMENTS OF EUCLID. Part I. Books I. -VI. With numerous Examples. Fcp. 8vo., 3^. 6d. A TREATISE ON THE ANALYTICAL GEOMETRY OF THE POINT, LINE, CIRCLE AND CONIC SECTIONS. Containing an Account of its most recent Extension. Crown 8vo., izs. HAMILTON. ELEMENTS OF QUATERNIONS. By the late Sir WILLIAM ROWAN HAMILTON, LL.D., M.R.I. A. Edited by CHARLES JASPER JOLY, M.A., Fellow of Trinity College, Dublin. 2 vols. 410. 2is. net each. LONGMANS' LIST OF APPARATUS FOR USE IN GEO- METRY, ETC. 1. LONGMANS' ENGLISH AND METRIC RULER. Marked on one edge in Inches, Eighths, Tenths and Five-fifths. Marked on the other edge in Centimetres. Price id. net. 2. LOW'S IMPROVED SET SQUARES. Designs A & B. 45 to 60. A i 60 4" ^ f B i 60 4" each i/- net. A i 45 4" "I (B i 45 4" each i/- net. A2456" ^or] 6245 6" ,, 1/3 ,, A 3 45 61" J lB 34S 8r 2/- A 2 60 6" orl B 2 60 6" ,, 1/3 A 3 60 8" J U 3 60 8" 2/- 3. LOW'S IMPROVED PROTRACTORS (Celluloid). Protractor No. 2. 3" radius, marked in degrees, 6d. net. Protractor No. 3. 4" radius, marked in ^-degrees, gd. net. 4. LOW'S ADJUSTABLE PROTRACTOR SET SQUARE. 2s. 6d. net. 5. LONGMANS' BLACKBOARD ENGLISH AND METRIC RULE. One Metre; marked in decimetres, centimetres, inches, half-inches and quarter-inches, ss. 6d.