Hope my cry's not in vain for this object with no name

Help needed to identify mysterious object

Among the hundreds of thousands of photographs held by the Library are some that remain a mystery to us. They have been acquired as part of albums or collections without any captions or other information that might help us to identify the people, objects or places in them.  Tantalizing and intriguing, we wish we knew more about them. They might be exactly what someone is looking for, if only we knew where/who/what they were! We just hate using that word "unidentified ..." in the titles of our catalogue records and do our best to track them down, but just don't have the knowledge or time to devote to the task.  Very frustrating! One of these "unknowns" that has aroused my curiosity is an object featured in a lantern slide from our John Flynn collection. John Flynn, founder of the Australian Inland Mission and the Royal Flying Doctor Service, was an avid photographer, amassing a wonderful collection of images of the outback, its inhabitants, and various pieces of machinery and equipment during his travels as a missionary in the early years of the 20th century. Flynn used some of these in lantern slide lecture tours around the country to raise  funds for his proposed Australian Inland Mission.

Flynn lecture advertisement

Flynn lecture advertisement

Now I wonder what his spiel was about this slide during his lectures? I'm sure he had a good reason for including it, and thought it was something interesting or significant.

Flynn photo - unidentified object

Flynn photo - unidentified object

It has me stumped, but I'm sure there is someone out there who could enlighten me so we could change our caption for this photograph from "Unidentified object, two egg-shaped bulbs joined by a tube" to something a little more meaningful. Please help!