The Sphere Feb 20th 1915. Zeppelin Navigation and Lightning Danger. £11.50 Quantity: at £11.50 each Add To Basket 1 in stock. Full page called - " Zeppelin Navigation and Lightning Danger." Showing how Zeppelin airships become electrically charged when flying free in the atmosphere and the dangers which result.These notes have been extracted and revised by a Sphere aeronautical expert from an article by Professor Dr. H. Sieveking of Karlsruhe.