I found this article in The Canadian Philatelist
A coming boom in revenues
It is but a matter of time ere revenue collecting becomes general. Every month sees its adherents increasing, and the demand for revenues and telegraphs becoming greater, and there is no reason, as far as I can see, why this branch of philately should not become as great or even greater than the sway exercised by the postage stamp at the present time.
Now, how is it that revenue stamp collecting did not, and is not as general as the collection of postage stamps? The revenue stamp was in use centuries before the idea of the postage stamp was conceived. The leading cause is the regulation regarding the use of this class of stamps. They are placed on documents, and usually the law requires that they be left there, otherwise the document in question shall have no legal value. This is not always the case. Again, papers such as are required to be stamped with revenues are not so commonly seen as the letters which are flying to and fro before our eyes daily. Their partial obscurity is one reason why they have not been generally collected.
A time of changes is coming. New adherents to fiscal collecting are becoming very numerous. Take the beginner, and it will be found that he almost invariably mixes revenues in with his collection of postage. He sees no reason why one has any more claim on him than another. He has an eye for beauty of colour and design. It will generally be found that he considers his revenues the pink of his collection.
Specialists of their native country invariably include revenues in their collections. Today we find many who collect nothing but revenues, and again others who collect both postage and revenues.
Revenue collecting is steadily gaining ground. We now have numerous catalogues of revenue stamps published. An enterprising London firm have recently commenced the publication of the Fiscal Philatelist, which will do much for the cause. The leading journals are beginning to take hold of the subject, devoting their space and effort to its advancement.
Do you collect revenues? If not, you should remember they have a strong claim on you, whether specialist or general collectors. You find in them a range of variety greater than in postage stamps. The size is, on the average, larger. The increased size gives room for artistic design such as is seldom seen in postage stamps. Taken all around, examination will show you that for beauty, colouring and exquisite original design, revenue stamps have this even more than postage stamps. Reader, think this over, and let your decision be that you will collect revenues, even though it be on a small scale. Now’s the time to begin. The demand at present is, comparatively speaking, small, and revenues can be bought at very low rates. But prices are steadily on the rise. As collectors increase, the prices do likewise. “A word to the wise is sufficient.” Those who begin before the demand becomes general are the wise; and the result will be apparent in the near future. “Never put off till tomorrow what you can do today.”