Radio techniques were the nrst to lead astronomy away from the quiescent and limited Universe revealed by traditional observations at optical wave lengths. In the earliest days of radio astronomy, a handful of radio physicists and engineers made one startling discovery after another as they opened up the radio sky. With this collection of classic papers and the extensive intro ductory material, the reader can experience these exciting discoveries, as well as understand the developing techniques and follow the motivations which prompted the various lines of inquiry. For instance he or she will follow in detail the several attempts to detect radio waves from the sun at the turn of the century; the unravelling by Jansky of a "steady hiss type static"; the incredible story of Reber who built a 9 meter dish in his backyard in 1937 and then mapped the Milky Way; the vital discoveries by Hey and colleagues of radio bursts from the Sun and of a discrete source in the constellation of Cygnus; the development of receivers and interferometry in the post-war years by the groups led by Ryle in Cambridge and Pawsey in Sydney; the nrst measurements and exciting identiftcations of Taurus A (the Crab Nebula), Centaurus A, Virgo A, Cassiopeia A, and Cygnus A, the last opening the neld of radio cosmology; the early development of synchroton theory; and the prediction and discovery seven years later of the 21 cm line of neutral hy drogen.

Inhalt
I. Galactic Background Radiation.- A. The Beginning of Radio Astronomy.- 1. Directional Studies of Atmospherics at High Frequencies.- 2. Electrical Disturbances Apparently of Extraterrestrial Origin.- 3. A Note on the Source of Interstellar Interference.- B. First Maps of the Galaxy.- 4. Cosmic Static.- 5. Cosmic Static.- 6. Cosmic Static.- 7. Cosmic Static.- C. Free-Free Emission Theory.- 8. Interstellar Radiation from Free Electrons and Hydrogen Atoms.- D. Synchroton Radiation and Cosmic Rays.- 9. Cosmic Rays as the Source of General Galactic Radio Emission.- 10. Cosmic Rays as the Source of Galactic Radio Emission.- II. Techniques.- E. The Dicke Radiometer.- 11. The Measurement of Thermal Radiation at Microwave Frequencies.- F. The Phase-Switched Interferometer.- 12. A New Radio Interferometer and its Applica¬tion to the Observation of Weak Radio Stars.- III. The Solar System.- G. Early Solar Searches.- 13. On an Attempt to Detect Electrodynamic Solar Radiation and on the Change in Contact Resistance when Illuminating Two Conductors by Electric Radiation.- 14. A Search for Hertzian Waves Emanating from the Sun.- 15. On the Search for Hertzian Radiation Emanating from the Sun.- H. Detection of the Sun.- 16. Solar Radiations in the 46 Metre Radio Wave-Length Band.- 17. Microwave Radiation from the Sun (with Erratum).- I. First Solar Interferometry.- 18. Solar Radiation on 175 Mc/s.- 19. Solar Radiation at Radio Frequencies and its Relation to Sunspots.- J. The Hot Solar Corona.- 20. Temperature Radiation from the Quiet Sun in the Radio Spectrum.- 21. Observation of Million Degree Thermal Radiation from the Sun at a Wave-Length of 1.5 Metres.- K. Lunar Radiation.- 22. Microwave Radiation from the Sun and Moon.- IV. Discrete Sources.- L. Discovery and First OpticalIdentifications.- 23. Fluctuations in Cosmic Radiation at Radio-Frequencies.- 24. Variable Source of Radio-Frequency Radiation in the Constellation of Cygnus.- 25. A New Intense Source of Radio-Frequency Radiation in the Constellation of Cassiopeia.- 26. Positions of Three Discrete Sources of Galactic Radio-Frequency Radiation.- M. Synchroton Radiation.- 27. Cosmic Radiation and Radio Stars.- N. Optical Identification of Cas A and Cyg A.- 28. An Accurate Determination of the Positions of Four Radio Stars.- 29. Identification of the Radio Sources in Cassiopeia, Cygnus A, and Puppis A.- O. Source Structure.- 30. Apparent Angular Sizes of Discrete Radio Sources.- 31. Apparent Angular Sizes of Discrete Radio Sources.- 32. Apparent Angular Sizes of Discrete Radio Sources.- 33. Fine Structure of Extra-Terrestrial Radio Source Cygnus I.- V. Spectroscopy.- P. Prediction of the 21-cm Line.- 34. The Origin of Radio Waves from Space.- Q. Prediction of Molecular Line Emission.- 35. Monochromatic Radio Emission from the Galaxy and the Possibility of its Observation.- R. Discovery of the 21-cm Line.- 36. Radiation from Galactic Hydrogen at 1420 Mc/s.- 37. The Interstellar Hydrogen Line at 1420 Mc/s and an Estimate of Galactic Rotation (with a short note from J. L. Pawsey).- References.- Name index.