Dr. Seward is using hollow wax phonograph cylinders to record his diary.
Invented in 1877, the phonograph was the first device able to reproduce recorded sound. Although the technology advanced quickly, and gramophone discs were already in development, the concept of recorded sound would still have seemed remarkably new and almost magical to Bram Stoker at the time of writing.
Modern technology and discovery, such as the phonograph, telegraph, typewriter, guns, medical drugs, and blood transfusions, feature throughout the book. The Victorian age was one of rapid advancement and invention, bringing a new confidence in the abilities of man and in the conquering power of science. However, superstitious fears and beliefs were also prevalent, in an era famous for both Darwin and its mediums. Dracula plays on these ideas, showing characters from a world of science and invention thrown into supernatural peril. When modern technology fails, they must turn their hopes to weapons of faith and superstition instead.
“Ah, it is the fault of our science that it wants to explain all; and if it explain not, then it says there is nothing to explain.” – Van Helsing