idea of life upon them as impossible or improbable
From DANAHAY 41: Reference to a Victorian debate regarding the existence of intelligent life on Mars. See Wells's article "Intelligence on Mars" in the Saturday Review 8 (April 4, 1896), p. 345-46.
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a man with a microscope might scrutinise the transient creatures that swarm and multiply in a drop of water
From DANAHAY 41: Wells was interested in the microscope to the point where he visited a microscope factory for his article "Through a Microscope."
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Exhibition Road
From HUGHES AND GEDULD 229: "a spacious thoroughfare in South Kensington, London. Location of the Imperial College of Science, formerly the Normal School of Science (part of the University of London), where Wells studied under Thomas Henry Huxley."
healthy or unhealthy livers
From DANAHAY 145: "Wells himself suffered from liver problems."
the case.
GANGNES: The 1898 version of the novel adds two paragraphs here about the thoughts of "a certain speculative writer of quasi-scientific repute" on Martian technology and anatomy. This is commonly thought to be a cheeky reference to Wells himself. See text comparison page.
Westminster to his apartments near Regent’s Park
GANGNES: Regent's Park is a large public park in the northern part of central London. It lies north of the Thames, and it would likely take the narrator's brother a little under an hour to walk there from the south, depending on where in Westminster he is and where his apartment is situated. Wells's final home was near Regent's Park.
From HUGHES AND GEDULD 232: Regent's Park is "central London's largest park, containing the London Zoo and the Botanical Gardens. It extends north from Marylebone Road to Primrose Hill; and west from Albany to Grand Union Canal."
cyclists
From MCCONNELL 130 and 152: Cycling was extremely popular in the 1890s; the safety bicycle was first patented in 1884, but the patenting of the first pneumatic tire in 1888 made cycling comfortable and affordable. Wells was learning to ride the bicycle around the time that he wrote this novel.
learning to ride the bicycle
From MCCONNELL 130: Wells was also learning to ride a bicycle during this time.