Dobson had this to say about mephitic vapours:

I can date my fanatical interest in mephitic vapours quite precisely. There was an autumn during my childhood when my parents took to sending me, at the first hint of daylight, on a morning errand to fetch eggs from a distant farm. There had been a falling out with the nearby eggman, for reasons unclear to me. I was sent out of the room on the last occasion he called, and heard muffled, undecipherable shouting, some thumps, and the slamming of the door. The next day I was roused at dawn and told to put on my wellington boots and head off across the fields, following a hand-drawn map pressed into my hands by papa. The map showed our hovel and a dotted line, with compass points, a few notable features such as a badger sanctuary and a Blötzmann mast, and at the end of the dotted line an egg, representing the distant farm. I would have had to be a peculiarly dimwitted child not to be able to make my way there and back by mid-afternoon.

But what papa omitted from the map, deliberately or otherwise, was Loathsome Marsh. This I had to splash through, in my wellingtons, twice a day until, months later, there was a rapprochement with the eggman. In spite of its loathsomeness, I grew to love Loathsome Marsh. I was particularly fond of the mephitic vapours which hung over it, morning and afternoon, a shroud of evil mist in which I fancied sprites and goblins cavorting and cutting capers. The noxious pong did not bother me, for I soon learned to plug my nostrils with cotton wool.

Years later, I had the pleasure of meeting a mephitic vapour scientist who was making a special study of Loathsome Marsh. One day he took me back to his laboratory, where I spent a happy afternoon poring over his baffling array of instruments and equipment while he explained his project to me. He too, it seemed, was convinced that the mephitic vapours of Loathsome Marsh served to half-conceal various sprites and goblins. He was, he said, trying to “isolate” them. He would go down to the marsh at daybreak, as I had done all those years ago, and scan the mephitic vapours with a mephitic vapour scanner of his own design. He then captured a sample of the mephitic vapours in a glass holder, its vent plugged with a simple cork from a wine bottle, and brought it back to the laboratory for analysis. Thus far, he admitted, he had no conclusive results to report, but I could tell from the mad gleam in his eyes that the mephitic vapours of Loathsome Marsh had quite unhinged him, and that his life thereafter would be devoted to them.

I have not been able to trace the out of print pamphlet from which this passage is taken. It appears in an anthology entitled The Bumper Book Of Mephitic Vapours For Boys And Girls, the editrix of which, one Prudence Foxglove, provides no sources for any of the four hundred and thirty-seven texts she cobbled together. There is a distinct possibility that she may have written the whole thing herself and attributed the separate pieces to writers both real and invented. I cannot be bothered to check on the others, but alongside Dobson we have passages on mephitic vapours purportedly by Rudyard Kipling, Ford Madox Ford, Dorothy Parker, and Anthony Burgess. Certain other pieces are credited to unknown authors who are probably figments of Prudence Foxglove’s imagination, such as Tex Beard, Gladiolus Frugmentor, and Jeanette Winterson.

Maddeningly, however, the passage I have quoted above certainly reads like Dobson. I had it analysed by an expert in textual authentication methods at the University of Ick-on-the-Ack, who gave it a rating of 93% on his own scale. He did not explain the scale to me, but there was something very persuasive about the expression on his large flat florid face when he reported his findings. Against that, he ran off at inhuman speed as soon as I handed over the cash payment he demanded.

So the jury is still out. One avenue we might prance along is to attempt to identify the mephitic vapour scientist Dobson (or Prudence Foxglove) mentions. If we can find a trace of him elsewhere in the pamphleteer’s work, this would I think settle the matter. Fortunately, hothead young Dobsonist Ted Cack has embarked upon precisely this approach, so I don’t have to. From his current location in a sink of vice and debauchery somewhere in the hinterland of Tantarabim, Ted Cack writes:

Ahoy there Key! Let me tell you what I have on my desk right now. To my right, a pile of Dobson pamphlets, both originals and illegal photocopies. To my left, the sixteen volumes of the New Standard Biographical Dictionary Of Mephitic Vapour Scientists, Revised Edition. And do you know what I am doing? When I am not canoodling with floozies and glugging vast quantities of 90% Proof Bestial Intoxicant and cheating at all-night games of Spite, I have been diligently cross-referencing the two piles. Sooner or later I am going to be able to match up a name from the Dictionary with a person mentioned in a pamphlet. Then my fame among Dobsonists will be as glorious and eternal as the star on Raymond Roussel’s forehead. The rest of you may as well pack your bags and slink off to wherever pathetic failed Dobsonists slink off to – splashing about helplessly in Loathsome Marsh, most likely. Toodle pip!

If Ted Cack does succeed in his research, I might well go slinking off as he suggests. But in order to do so, I would have to know the location of Loathsome Marsh, and that, too, is a mystery.