Please be sure to review all my other auctions after you have looked at this one! I will be listing a broad and diverse range of vintage communications and technology items, related books, periodicals and ephemera... Something for everyone!This is something that you are not likely to ever see again. It is a Bell Gap Quenched Rotary Spark Gap made by The Electric Machine Company of Indianapolis, Indiana and is in excellent condition!! It stands an impressive 9.5" tall..., is 9.75" wide and over 8" deep to the end of the electrodes. These beasts were a Machinist's ideal at the time...a "Work of Art"! Rugged and robust, the Bell Gap incorporates a cast housing, glass vision inserts, massive stand-off insulators for the adjustable electrodes, a hardened, tool steel rotating shaft, precision ground to the nearest .001" and nestled into bronze bearings equipped with an oil ring lubricating system and a large oil sump!! The rotary gap wheel has twelve (12) wide teeth that react with four copper sparking surfaces mounted on adjustable electrodes, two on each side of the housing... The electrodes are adjustable from the outside while the operator watches through the glass windows on either side of the housing! Short leads, ease of operation and functional reliability made the Bell Gap a amateur's delight! These units were well known for their distinctive and pleasant tone..."Clear as a Bell"...as they say!!I have only seen one other Bell Gap "in the wild " in over 40 years of collecting!! I have tried to take good photographs, and they represent the condition of this historical device quite well. If you have any questions, please ask!!Put this remarkable rotary gap on your shelf...or match it up in the basement with a nice transformer and glass plate condenser and create some light...:)Packaged to arrive safely at your door, shipping weight will be about 16.5 pounds!!I will pack all items properly and with great care. I have been shipping these kind of vintage items worldwide since the late 1980's. Buyers are responsible for shipping, insurance and material costs and any applicable duties. Illinois residents must pay 6.25% sales tax. I usually can ship within one business day after receipt of confirmed payment. International customers are welcome! Bid with confidence as international shipping is not an issue!If you are new to eBay with no prior feedback please contact me prior to bidding...thanks! THANK YOU FOR LOOKING!