Update
Updates on past articles: Survex, Watsonlinc, Alkaline Cells for Lighting, SSB fourth Method, Solar-power Charger, Cell-Zapper, Bibliography.

Geophysical Cave Detection, part 2
Phil Ingham summarises the use of seismic, gravitational, magnetic, electrical and electromagnetic techniques.

A High-performance Flashgun Slave
David Gibson presents a practical design which is compact, has a high range, in insensitive to caplamp beams and consumes a very low current.

A Bit of Flash Gear
Chris Howes gives some practical hints on using flashbulbs.

The State of Cave Surveying
A roundup of what has been happening over the last few years by Dave Irwin, together with a reading list.

Cave Radio PA Design and a Digital PWM DSB Modulator
David Gibson's experimental design.

Radio Initiation of Detonators
Phil Ingham reveals how to avoid blowing yourself up whilst using radios underground.