This class of literature was of considerable dimensions even in the days when Mr. Wilkie Collins first called attention to it; but the luxuriance of its growth has since become tropical.  His observations are drawn from some half a dozen specimens of it only, whereas I now hold in my hand—­or rather in both hands—­nearly half a hundred of them.  The population of readers must be dense indeed in more than one sense that can support such a crop.

Doubtless the individual circulation of none of these serials is equal to that of the most successful of them at the date of their first discovery; but those who read them must, from various causes, of which the most obvious is the least important, have trebled in number.  Population, that is to say, has increased in very small proportion as compared with the increase of those who very literally run and read—­the peripatetic students, who study on their way to work or even as they work, including, I am sorry to say, the telegraph boy on his errand.

Nevertheless, notwithstanding its gigantic dimensions, the Unknown Public remains practically as unknown as ever.  The literary wares that find such favour with it do not meet the eye of the ordinary observer.  They are to be found neither at the bookseller’s nor on the railway stall.  But in back streets, in small dark shops, in the company of cheap tobacco, hardbake (and, at the proper season, valentines), their leaves lie thick as those in Vallombrosa.  Early in the week is their springtime, when they are put forth from Heaven knows what printing-houses in courts and alleys, to lie for a few days only on the counter in huge piles.  On Saturdays, albeit that is their nominal publishing day, they have for the most part disappeared.  For this sort of literature has one decidedly advanced feature, and possesses one virtue of endurance—­it comes out ever so long before the date it bears upon its title-page, and ‘when the world shall have passed away’ will, by a few days at least, if faith is to be placed in figures, survive it.

Why it should have any date at all no man can tell.  There is nothing in the contents that is peculiar to one year—­or, to say truth, of one era—­rather than another.  As a rule, indeed, time and space are alike annihilated in them, in order to make two lovers happy.  The general terms in which they are written is one of their peculiar features.  One would think that, instead of being as unlike real life as stories professing to deal with it can be, they were photographs of it, and that the writers, as in the following instance, had always the fear of the law of libel before their eyes: 

  We must now request our readers to accompany us into an obscure cul
  de sac opening into a narrow street branching off Holborn.  For many
  reasons we do not choose to be more precise as to locality.

Of course in this cul de sac is a Private Inquiry Office, with a detective in it.  But in defining even him the novelist gives himself no trouble to arouse excitement in his readers:  they have paid their penny for the history of this interesting person, and, that being done, they may read about him or not, as they please.  One would really think that the author of the story was also the proprietor of the periodical.