The Science Fiction Encyclopedia contains an entry for one Avis Hekking noting her authorship of the SF novel A King Of Mars, published in the UK by John Long in 1908. With such an odd name, it ought to be possible to find out something about her.
I got a hit in the 1881 British census which said she was born in New York, c. 1841; she also had 3-year-old daughter, also called Avis, born in Jersey, Channel Islands and a 6-month-old baby, Frank, born in New York. The family were lodging at 1 Crane Grove, Holloway, London, at the time of the census but, given Frank's place of birth, they had probably not been resident long.
Another daughter, 15-year-old Christine Hekking (b. New York) was at school at Hampton College, Hampton Road, Middlesex.
The 1870 US census has an Avis Hecking, b. Michigan, c. 1840, the wife of Antonie Hecking (a landscape painter), then a housewife in New York. The husband would appear to be Joseph Antonio Hekking (1830-1903, the form of name under which he appears in Who Was Who in American Art), who worked in Michigan. You can find out more about J. Antonio Hekking by doing a Google search, but for a quick summary of his career, you might try here. I've illustrated this piece with a few of his paintings but you can find plenty of others dotted around the web.
Johannes Antonius Hekking was born in Nijmegen, Netherlands, on 19 June 1830, the son of Franciscus Josephus Hekking and his wife Grada Scheerder. He was the father of Charles Raijmundus Hekking, born in Hees, Netherlands (25 June 1867), who is one of the Hekking children listed on the 1870 census (the other being 5-year-old Christine). His mother was listed as Avis Selina Clarke.
A bit of further digging turns up the fact that Avis Clark Hekking (using the American style of incorporating parental and married surnames) was the daughter of John P. Clark and Susan Booth and was born in Detroit, Michigan. The 1850 US census Avis was listed as an 11-year-old, implying a birth in c.1838/39; the 1860 census gives her age as 20, which, again, gives her a year of birth of 1839/40.
Putting all this together we get Avis Selina Clark Hekking, b. Detroit, Michigan, c.1839. A little different to the b. New York, c.1841 I originally discovered in the UK 1881 census.
The next question that needed answering was this: was it Avis Hekking, the mother, or Avis Hekking, the daughter, who wrote A King of Mars. The daughter, if she was born in c.1877/78, would have been around 39 or 40 when the novel was published. Her mother would have been 70. My gut feeling was that the book would have been written by the daughter. But how to prove it?
The only sign of her is a series of 23 letters written to Oscar Browning in 1899-1907. Browning was a master at Eton and King's College, Cambridge, and an author of various non-fiction works (Wikipedia has an entry for him); his letters and papers are held by the National Archive which describes the letters above as coming from "a young lady (possibly American) living in Europe with her parents; she was a close friend of Fred Harvey." Frederick Ernest Edwin Harvey was Browning's secreatary
Avis Hekking wrote only two novels as far as I can determine:
In Search of Jehanne. A romance. London, John Long, 1907
A King of Mars. London, John Long, 1908.
The former is described in an advert as "A new historical romance which can bring effectively before the reader the life and manners of a bygone age, and make real flesh and blood of the characters which it introduces, is a rarity, and sure of a warm welcome. Such is "In Search of Jehanne." Miss Avis Hekking has taken the sixteenth century and the Massacre of the Huguenots as a background. The characters are French, and the events happen wholly in France. " In Search of Jehanne" is a romance of first-rate quality, and it should create for the author a high position among writers of historical novels."
Note the "Miss" attached to Avis Hekking. It must be the daughter. But what happened to her? Her next book was about communications between the moderately advanced inhabitants of Mars and Earth... after which she seems to have disappeared from the planet herself, although it was probably only to Europe as implied by the National Archives.