50 Years Ago

The Royal Navy last week broke the world record for deep diving on dry land by taking two volunteers to an equivalent of 1,500 feet in a pressure chamber. The subjects endured ten hours in an atmosphere of oxygen and helium at 666 pounds/inch2 (just over 45 atmospheres) and spent the next eleven days in a gradual mock ascent … There is no sign yet of any physiological limit for diving, and at least a further 300 feet of the sea are now opened up to explorers who take the requisite precautions. Besides the intrinsic interest of seeing what depths the human frame can attain, the experiment has provided an opportunity for studying the tremors and dizziness often suffered when high-pressure helium mixtures are breathed, and at the same time has made possible a wide range of physiological observations which have yet to be analysed. Because of the experimental nature of the exercise, frequent safety checks were made during the descent; the subjects paused for 24 hours at a time in atmospheres corresponding to 600, 1,000 and 1,300 feet, and made intermediate one-hour halts at 1,100, 1,200 and 1,400 feet. One of the subjects was temporarily affected by helium tremors after changes of pressure, but the other only suffered from occasional dizziness. It seems that limitations of time rather than physiology are the chief obstacle to really deep dives.

From Nature 21 March 1970

100 Years Ago

An interesting lecture on the history of electrotherapy by Dr. W. J. Turrell is published in the Archives of Radiology and Electrotherapy for February … In England electrical treatment appears to have been first practised by the clerical profession. In 1756 a book on the subject was published at Worcester by Richard Lovett, a lay clerk at the cathedral, in which he records the treatment of a number of diseases with electricity. In 1780 John Wesley, the great divine, anonymously published a book entitled “The Desideratum; or, Electricity made Plain and Useful.” In this he appeals to the medical profession for a trial of the curative effects of electricity, and records many alleged cures.

From Nature 18 March 1920