In other studies he found that a wide variety of organisms displayed responses to gravitational, magnetic and electrical fields leading him to propose exogenous factors as controllers of biological rhythms.

[8] His work and ideas ran counter to the prevailing trend in chronobiology at the time, which was focused on the development of the endogenous and bio-chemical model of the circadian clock.

[9] Brown envisioned the biological clock as being a duality in which an internal responder to subtle information from the environment is overlain by an endogenous timing mechanism.

[9] A paper published in Science magazine in 1957[10] criticised a methodology of finding cycles with environmental fluctuations, was believed to be at least partly directed at Brown.

[11] Brown continued to study rhythms up to his death in a series of experiments documented in published scientific papers on correlations with magnetic fields, gamma rays and other subtle signals in the natural environment.