Section Drawing Research Articles

RECENT ADVANCES IN THE CONSTRUCTION OF THE OPHTHALMOSCOPE

At the International Ophthalmological Congress at Amsterdam in 1929 a number of electric ophthalmoscopes were exhibited which were either unknown or little known in America. After examining these instruments and later temporarily possessing several of them it seemed that it might be of interest to supplement the excellent articles of Graves, Landon and Friedenwald and describe the advances in ophthalmoscopic construction in the last ten years. Several of my friends in foreign clinics have supplemented my own observations with their experiences with instruments that I have not personally used, and a number of manufacturers of ophthalmoscopes provided me with sectional drawings and particulars of the construction of the instruments. The electric ophthalmoscope is readily divisible into several component parts, such as the observing lenses, light source, condensers, diaphragms, color filters, mirrors, measuring devices and slit-lamp illumination adjustments. Of all these divisions the viewing lenses have changed

Modern Lithology, illustrated and defined, for the use of University, Technical, and Civil-Service Students

THE excellent microscopic drawings of rock-sections previously issued by Mr. Adye (see NATURE, vol. lxxi., p. 341), in a work entitled “The Twentieth Century Atlas of Petrography,” prepare us for the present series of sixteen smaller plates. With four coloured figures on each, some of them subdivided into two semicircles, we have a wide range of rocks accurately and artistically represented. The drawing and de scription of thin sections is not strictly “lithology,” however “modern” it may be; but Mr. Adye deals with the illustrations clearly in the accompanying text. He also gives a glossary of petrographic terms, which contains many useful references to original papers. Modern Lithology, illustrated and defined, for the use of University, Technical, and Civil-Service Students. By E. H. Adye. Pp. 128. (Edinburgh and London: W. and A. K. Johnston, Ltd., 1907.) Price 10s. net.

Cassell's Technical Manuals—I

THESE little books are intended to promote the technical education of artisans, and seem to be well-adapted to facilitate the work of teachers and learners. The manual of Linear Drawing shows the application of practical geometry to trade and manufactures, and has been appropriately chosen as the first volume of a technical series for craftsmen. The methods of constructing geometrical figures are given without the mathematical proofs which usually accompany such problems. The application of some of the figures to decorative and mechanical work is illustrated in diagrams of the trefoil, quatrefoil, toothed wheel, ellipse, &c. Accuracy is persistently inculcated, and all the figures are admirably executed. The manual of Projection leads the student many steps further, and treats of the drawing of plans, elevations, and sections of solids. The chapter on isometrical projection explains that system of drawing in a clear and concise manner. In some of the more elaborate figures fewer lines of construction might have been used with advantage. The observations on drawing instruments, and their use, are thoroughly practical. The third treatise elucidates the principles of Building Construction, and gives some useful hints on architectural drawing. It is profusely illustrated with diagrams; these are generally good, but the minor details of a few need correction. Cassell's Technical Manuals.—I. Linear Drawing. 2. Projection. 3. Building Construction. By Ellis A. Davidson. Price 2s. each. (London: Cassell, Petter, & Galpin.)