Speaking of Nevin’s electronics, his last major invention for caving (as far as I know) was a system to detect airflow connections between caves. This was like a very sophisticated “stink bomb” experiment, the air equivalent of a dye trace. At one entrance, a fan would be set up that would automatically reverse direction every few minutes. At another entrance he set up an extremely sensitive ultrasonic anemometer that he designed and built. Each device was connected to a data logger that recorded the timing. If the two caves were connected, the anemometer would record a square wave of airflow, reversing at exactly the same rate as the fan. There’s no way that could happen naturally.
We used this system several times in the Burnsville Cove (Butler Cave area) in Virginia and found some interesting air connections. Some of those connections were not obvious and didn’t need to be passable, as long as the air could move through, just as for a dye trace with water. It worked really well, the only limitation being that the entrances had to be confined enough to direct the airflow in and out. This was easiest if the entrance was gated, but could also be accomplished with tarps. Mark Minton mmin...@caver.net From: Texascavers [mailto:texascavers-boun...@texascavers.com] On Behalf Of Dwight Deal Sent: Saturday, March 20, 2021 2:55 PM To: texascavers@texascavers.com; Mark Minton Subject: Re: [Texascavers] Nevin Davis I knew Nevin from Pennsylvania/Butler Cave. He also was an inspired inventor, having built a motorized ascender (MAD I think he called it, for Motorized Ascending Device). Nevin used it to come out of Golendrinas. I think he modified a chain saw engine. He also was an electronic wizard. Somewhere I still have one of his fluorescent light headlamps, which was the first (and possibly only) electric headlamp that duplicated the broad glow and visibility provided by a carbide lamp. In my opinion the light provided was even better than the carbide lamp. DirtDoc
_______________________________________________ Texascavers mailing list | http://texascavers.com Texascavers@texascavers.com | Archives: http://www.mail-archive.com/texascavers@texascavers.com/ http://lists.texascavers.com/listinfo/texascavers
