Definition of "oil-gland" [oil-gland]

• In ornithology, the uropygial gland of birds, which secretes the oil with which they preen and dress their plumage; the elæodochon. It is a highly developed and specialized sebaceous follicle, present in the great majority of birds. See cut under elæodochon. (noun)

The Century Dictionary (Public Domain)

• "They are not only light and strong, but warm, and by their means, as a bird soars into colder regions of air, it is protected from the cold: while for aquatic birds there is a special provision -- by pressing with their beaks an oil-gland near the tail they can waterproof their feathers!"
• "After this touch the bill, orbits, feet, and former oil-gland at the root of the tail with the solution, and then you have given to the hawk everything necessary, except attitude and a proper degree of elasticity -- two qualities very essential."
• "The fantail has thirty or even forty tail-feathers, instead of twelve or fourteen—the normal number in all the members of the great pigeon family: these feathers are kept expanded, and are carried so erect, that in good birds the head and tail touch: the oil-gland is quite aborted."