  During the 1960s, a small but vibrant community of cosmic ray physicists,
pioneered novel optical methods of detecting extensive air showers (EAS) in the
Earth's atmosphere with the prime objective of searching for point sources of
energetic cosmic gamma-rays. Throughout that decade, progress was extremely
slow. Attempts to use the emission of optical Cherenkov radiation from showers
as a basis for TeV gamma-ray astronomy proved difficult and problematical,
given the rather primitive light-collecting systems in use at the time, coupled
with a practical inability to reject the overwhelming background arising from
hadronic showers. Simultaneously, a number of groups experimented with passive
detection of radio emission from EAS as a possible cheap, simple, stand-alone
method to detect and characterise showers of energy greater than 10^16 eV. By
the end of the decade, it was shown that the radio emission was quite highly
beamed and hence the effective collection area for detection of high energy
showers was quite limited, diminishing the effectiveness of the radio signature
as a stand-alone shower detection channel. By the early 1970s much of the early
optimism for both the optical and radio techniques was beginning to dissipate,
greatly reducing research activity. However, following a long hiatus both
avenues were in time revived, the optical in the early 1980s and the radio in
the early 2000s. With the advent of digital logic hardware, powerful low-cost
computing, the ability to perform Monte Carlo simulations and above all,
greatly improved funding, rapid progress became possible. In time this work
proved to be fundamental to both High Energy Gamma-ray Astronomy and Neutrino
Astrophysics. Here, that first decade of experimental investigation in both
fields is reviewed.
