[42] A. M. MATTSEN and others, _Journal of Agriculture and Food Chemistry_ (1955), vol. 3, p. 319. [43] JOHN B. VAN WAZER, _Phosphorus and its Compounds_, 2 vols. (vol. 1, _Chemistry_; vol. 2 _Technology, Biological Functions and Applications_, New York: Interscience, 1958, 1961. * * * * * Paper 40 - Transcriber's Note The following typographical errors have been corrected: Page 180 "Abfällen, Vieweg, Braunschweig," - had "Viewig". Page 188 "wires d from the dynamo D" - had "dynano". Page 192 "But phosphatides occur" - had "phosphatide soccur". Page 193 "the nucleic acid from the thymus" - had "nucleidic". Page 199 "acetylcholine esterase." - had "acetylcholin". Page 200 "George de Hevesy, Carl F. Cori," - comma added after Hevesy. Footnote 39: "See, e.g., Chemical Week, vol. 77" - had "See. e.g." The spelling of "Bertholet" [Claude Louis Berthollet] is as given on the original title page of the work referenced in this paper. Inconsistent hyphenation of chemical names has been retained. * * * * * CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY. PAPER 41 TUNNEL ENGINEERING--A MUSEUM TREATMENT _Robert M. Vogel_ INTRODUCTION 203 ROCK TUNNELING 206 SOFT-GROUND TUNNELING 215 BIBLIOGRAPHY 239 FOOTNOTES _Robert M. Vogel_ TUNNEL ENGINEERING--A MUSEUM TREATMENT [Illustration: Figure 1.--MINING BY EARLY EUROPEAN CIVILIZATIONS, using fire setting and hand chiseling to break out ore and rock. MHT model--3/4" scale. (Smithsonian photo 49260-H.)] _During the years from 1830 to 1900, extensive developments took place in the field of tunneling, which today is an important, firmly established branch of civil engineering. This paper offers a picture of its growth from the historical standpoint, based on a series of models constructed for the Hall of Civil Engineering in the new Museum of History and Technology. The eight models described highlight the fundamental advances which have occurred between primitive man's first systematic use of fire for excavating rock in mining, and the use in combination of compressed air, an iron lining, and a movable shield in a subaqueous tunnel at the end of the 19th century._ THE AUTHOR: _Robert M. Vogel is curator of heavy machinery and civil engineering, in the Smithsonian Institution's Museum of History and Technology._ Introduction