Hoffmann (Professor), 1839-1919., Plate, Adrian, inscriber., Harry Houdini Collection (Library of Congress) · New York : E.P. Dutton & Co. ; London : George Routledge & Sons, 1904. · leaf 89
Later Magic | 59 In my own opinion, neither of these plans is entirely satisfactory. What is needed is some form of terminal which shall effectually cut off the gas till needed, and on the other hand, when it escapes, shall allow it to do so in a diffused form. I would suggest some such appliance… … Fic. 49. hollow egg, of some hard wood, two inches in length by one and one quarter in diameter, and divided in half, - internally, by a diaphragm, bb, perforated (as would be also the upper half of aa) with several holes. These would usually be kept closed by the contact of a disc d, connected…
