Remarks on engineers' surveying instruments : (established 1870)

Incluye 4 folletos.Notas a pie de página.El primer mapa incluye el título: Topographical conventional signs. (To accompany Heller & Brightlys' "Remarks on Engineer's Surveying Instruments."). Compiled by Lewis M. Haupt., Professor of Civil Engineering, Universityt of Pennsylvania.El segundo mapa incluye el título: Study of contours. Walnut street. To acompany Heller Brightly's "Remarks on Engineer's Surveying Instruments". Vertical sections on AB and CD. Reduced from a Plane Table, Survey made by the C.E. Section of the Class of'76, University of Pennª.El Tercer mapa incluye el título: Lines of equal magnetic variation for the United States. Declination of the magnetic needle. (for the year 1891). Published by Charles S. Heller, Philadelphia, PA. (Copyrighted, 1892, by Charles S. Heller).