There should also be a Card-Tray, or abox with compartments in it, such as shown in thefollowing illustration. Of course the Tray might havean open top.
Miles suggests using a Card-Tray (in 1899) with various compartments and potentially an open top rather than some of the individual trays or card index boxes which may have been more ubiquitous
This shows a slight difference at the time in how an individual would use one of these in writing versus how a business might use them in drawers of 1, 2, 3 or cabinets with many more.
The image he shows seems more reminiscent of a 5x3" library charging tray than of some of the business filing appliances of the day and the decade following.
very similar to the self-made version at https://hypothes.is/a/DHU_-If6Ee-mGieKOjg8ZQ